Persuasive Determinants in the Hotel Industry’s Newsletter Opening Rates

Abstract

Email marketing plays a key role in business communications and is one of the most widely used applications by consumers. The literature review points to several determinants that, when applied, increase the open rate of newsletters. This research evaluates the impact of six determinants of persuasion on the opening rate of a newsletter in the hotel industry. The determinants are the day of sending, the time of sending, subject line personalization, scarcity appeal, curiosity appeal, and authority figure. The chosen methodology focused on real experiments, using a high-end luxury hotel, and the respective customer database. The newsletter was sent to the subscriber list, where one part received the control and the other part received a variant with the test version. Ten A/B tests were conducted for each determinant. The results obtained were not in line with what is indicated in the literature review. Although the literature review yielded results that showed that the application of determinants increased the open rate of newsletters, this study obtained findings to the opposite and did not confirm what was prescribed by the reviewed literature. The results of the A/B tests were conclusive and revealed that the determinants did not increase the open rate of newsletters.

1. Introduction

A sustainable communication channel is a form of communication that is not harmful to the environment and is environmentally friendly. Videoconferencing, instant messaging, and email are some examples of sustainable communication channels. These methods of communication can be used for both personal and professional purposes without using any resources or creating waste. To lessen our influence on the environment and safeguard natural resources, it is crucial to employ environmentally friendly communication methods. Email marketing has the potential to be a long-lasting method of communication and is environmentally friendly, but it must be used with consideration for other people’s time and attention. This entails sending emails only to those who have expressly consented to receive them and ensuring that the emails’ content is pertinent and useful to their receivers. Email marketing can be an efficient and valuable tool for communicating in the hotel industry. It can be used to send personalized communications to guests, such as reservation confirmations, special offers, and reminders about forthcoming events or activities. It can also be used to send newsletters and keep guests informed, delivering useful information about the hotel and its services. Additionally, email marketing can be used to solicit feedback from guests and gather insights about their experiences, which can be used to improve the overall quality of the hotel experience. Overall, email marketing can be an effective communication tool for the hotel industry and it is used widely in the tourism industry [1].

The usage of the internet is expanding, and communication through it is becoming commonplace in today’s culture [2] and the possibility for information distribution has increased as a result of people using email more often for interpersonal contact [3]. Therefore, email marketing is becoming more widely acknowledged as a practical and highly successful communication technique. The majority of people have access to email, which is for the most part free, straightforward, and quick to use, making it one of the most significant and effective tools for forging personal connections with customers [4]. Additionally, email marketing is regarded as one of the most significant information channels in terms of ROI (return on investment), and businesses highly regard this instrument [2]. Email enables the business to contact more customers with fewer resources and generates exponential returns [4].

Despite the resemblance to magazine and newspaper advertising, email marketing involves a variety of tactics and representations, making it a considerably more sophisticated marketing strategy [5]. Thus, email marketing is both a highly difficult and effective instrument for achieving business objectives [6]. Due to limited marketing resources, businesses, particularly those in the hotel industry, have actively sought for proactive and dynamic e-placement technologies to cut expenses [7]. More and more hotels are using email marketing as a flexible and affordable strategy to connect with their customers and agencies or operators directly [8]. With the expansion of campaigns, there has been an increase in the volume of emails from businesses, overflowing readers’ inboxes and making it challenging for users to choose which emails to open and read [9]. As a result, the strategies used to carry out email marketing campaigns have a direct impact on how effectively consumers are attracted to or are persuaded to open and read their emails [10].

To capture users’ attention and pique their interest in the campaign provided, many factors that determine whether a newsletter is opened are employed. These factors include the format, sender, subject lines, and hyperlinks [5]. The reach of the message to the desired target audience can be directly impacted by minor modifications to the email messages that are delivered. Regarding the factors that lead to better email communication, there is, nevertheless, a great deal of ambiguity, speculation, and opinion [6].

This research will be focused on evaluating six major determinants that are persuasive elements of opening email marketing campaigns based on the literature analysis that was conducted: the day of sending, the time of sending, and the subject line. The subject line is divided into the following factors: curiosity, personalization, scarcity, and authoritative sender. In addition to proving the effectiveness of email marketing campaigns, assessing the outcomes allows us to better understand and focus marketing efforts to achieve the desired results [6].

To understand how their proper use might optimize campaign outcomes, the research’s primary goal is to analyze the determinants and persuasive elements that lead to the opening of a newsletter. We may conclude that the primary research question is: “What is the impact of persuasive strategies as predictors of opening a newsletter in the hotel industry?”. Throughout this study, we will show that the determinants indicated above do not increase the open rate of newsletters, this being their greatest contribution.

2. Literature Review

The following five arguments support the relevance of this problem as a subject for research. Since there are not many studies specifically looking at email marketing and its effectiveness as a marketing strategy, this research first contributes to the academic community [11]. This means that published publications on email marketing and factors influencing newsletter opens are highly diverse in terms of the goals attained and the strategies employed [6]. The third argument is based on the fact that major businesses typically do research on the effects of email marketing on consumer behavior but do not publicly release the findings [12]. Additionally, it should be emphasized that the tourist industry generally lacks published publications, particularly in the hotel industry [8]. The fifth and final argument makes the point that, in terms of the business world, research serves to emphasize the significance of learning how businesses can track and evaluate marketing initiatives to produce better outcomes [5].

2.1. Persuasion

Persuasion is an old and well-defined concept [13] (p. 7): “Persuasion is achieved by the speaker’s personal character when the speech is so spoken as to make us think him credible”.

Human communication that aims to sway the free will and acts of another is known as persuasion [14] (p. 7), an experimental art form that involves the persuader and the person being convinced in a meticulously choreographed dance [15] (p. 34). This method works by sending out a variety of messages—oral or written—that are intended to change the recipients’ knowledge, opinions, and interests [16]. The art of persuasion and the capacity to be convinced are regarded as the cornerstones of society’s interactions because of the significance they imply [17].

2.2. Origin and Evolution of Persuasion

Ancient Greece is where the science of persuasion began and it is the cradle of rhetoric [18] (p. 2). Notable figures such as Plato and Aristotle were influential in this field [16]. In the rhetorical canon, the study of persuasion has a long and famous history. The necessity to educate citizens gave rise to rhetoric, which has historically focused on persuasion and civic ethical approaches [18] (p. 15).

Effective and persuasive communication is supported by rhetoric, which is at the core of persuasive communication [19]. The origin and purpose of rhetoric may be traced back to the art of effective communication, which results in the creation of coherent and rigorous speech [20]. This art is, in part, the methodical study of persuasion, where it is acknowledged how important it is to employ this strategy in our daily actions [19,21]. Everyday interactions and communication include rhetoric, which is also the primary medium for coordinating social action [22]. “Wherever there is persuasion, there is rhetoric. And wherever there is meaning, there is persuasion” [23] (p. 72).

Since it is inconceivable that ancient peoples did not employ this method to acquire the advantages connected with persuasion, it is difficult to pinpoint the genuine beginning of rhetoric as a persuasion art [24]. However, as rhetoric was one of the people of Greece’s principal objectives, it can be said that they were its primary facilitator [20]. The Greeks were the only people in ancient times to devote themselves to an ongoing study of human communication, its fundamental elements, and its primary outcomes [25] (p. 26).

Ethos, Pathos, and Logos—three different and integral Aristotelian elements—define classical rhetoric [26]. Ethos is a term used to describe the credibility and trustworthiness of the communicating entity [21]. While pathos is more concerned with the audience’s sentiments and relies on evoking strong emotions such as pity, terror, pleasure, sadness, and fulfillment to be convincing [26], the final definition of logos is the presentation of an argument’s integrity, usefulness, and clarity [27]. It is crucial to note that in rhetoric, logos refers to more than simply rationality; it is also the appearance of rationality, or what can be called “common sense” [28]. These three criteria outline the qualities of a strong argument and specify the parameters of compelling appeals [27]. As occurs whenever an old model of thought fades and a new one is hesitant to emerge, rhetoric has risen from its ashes after being reduced to fine style for more than two centuries [25] (p. 20).

This is how the development of mass media, the excessive use of propaganda, and the manipulation of the common people for economic or political gain influenced many new studies about rhetoric that were published in the 20th century. These studies were based on historical, linguistic, literary, philosophical, political, and psychological research [29].

2.3. Email Marketing Campaigns

Email marketing is a new channel that businesses may use to sell and publicize their new products and services as a result of the expansion of the Internet [30]. This kind of marketing involves delivering advertising, business proposals, or sales to present or potential customers directly, to increase brand awareness, loyalty, and trust [31]. Because it has several features that enable the business to interact with its customers, such as branding (making the company known to a potential customer), increasing consideration (accelerating the customer’s interest), conversion (getting a sale), product use (stimulating interest), retention, and customer loyalty, email marketing has become more and more popular for marketing campaigns [32]. Email marketing can also be used to raise awareness, improve the corporate image, or develop customer management [33]. Emails are also used in another context, such as triggered emails which are personalized messages that are automatically activated when an event occurs, such as a shopping cart abandonment [34], are used to encourage repeat purchases by predicting the optimal date and time to send personalized messages [35], or are just used to send information to subscribers [36].

Nevertheless, one has to point out that despite the profitable nature of email marketing, customers are overloaded with information, both wanted and unwanted [37]. It is also noteworthy that email marketing has implications for the consumer’s decision-making process [34]. Furthermore, as described by Hartemo [38], email lets an effective, collaborative, and personalized message achieve the preferences of consumers and can be used to empower consumers by dispatching emails built on authorization, by getting consumers to be effective contributors in the communication process and by producing emails pertinent to them. However, the author clearly stated that present email marketing strategies require revision to get the maximum value from the channel. Zhang et al. [39] also supports the previous statements.

Small firms must create strategic strategies, set attainable targets, and build their databases to strengthen their marketing departments and increase sales [31]. Getting people’s attention is important, but will not always result in their understanding, acceptance, or the correct reading of the message [40] (p. 26). There are several ways to send email marketing communications, including through websites, product catalogs, and newsletters [5]. The primary distinction between newsletters and the other strategies is that newsletters are meant to foster long-term connections between sender and receiver, whereas email requests rapid action from the recipient. Newsletters strive to provide readers with additional value and are more individualized and educational [41]. Email marketing initiatives are becoming seen as a powerful marketing technique [42].

2.4. Persuasion Factors and Determinants That Influence the Opening of a Newsletter

Users get an excessive quantity of emails, therefore they sort and prioritize which ones they want to read to shield themselves from the information [43]. Early campaign research has revealed that advertising execution strategies are connected to grabbing users’ and customers’ attention [10]. The following three phases of newsletters are crucial to the success of an email marketing campaign: getting clients to open the email is step one; getting them to read it is step two; getting them to click on the links that lead to the suggested website or promotion is step three [44,45]. It should be noted that the opening rate, being the first stage, actually impacts the purchase conversion rate [46]. It is therefore possible to state that we are in the presence of the theory of the hierarchy of effects [47].

The first phase is the main topic of this study. When a customer receives an email, they decide whether or not it would be of interest. The choice is made in light of prior experiences with other marketing initiatives and the topic line’s apparent relevance [43] but also of the possible association with persuasion. Everyone likes to believe that their actions are justified and that they are the product of intentional, deliberate thought. However, researchers contend that making decisions is not entirely controlled by our conscious thoughts [48]. For instance, persuasive messages are crucial in persuading readers to believe or act a specific way, whether or not they are conscious of doing so [18] (p. 21). Every human contact, from politics to marketing, to regular interactions with friends, family, and coworkers, is considered as requiring the use of persuasion [49]. The timing of email sending in terms of the day of the week and the time of the day, which might affect the opening of newsletters, is a crucial consideration when creating an email marketing campaign [5]. In reality, minor factors, which are almost ignored or little studied, exert persuasion on subscribers, as is the case with emojis, as was reported by Valenzuela-Gálvez, et al. [50], where the authors found that emojis affect customer engagement, can trigger collaborative behaviors, increase customer engagement, increase the probability of opening the email, and increase the number of times an email gets opened and the number of click to retrieve additional content.

When receiving an email, two components are displayed in the inbox that may draw the reader’s attention: the first is the sender, who identifies who the incoming email is from; the second is the subject line, which determines if the email will be of interest or not [5]. The most important elements influencing email opening are the subject line and the sender [51]. However, the subject line influences an email’s open rate 3.8 times more than the sender does [43].

2.4.1. Sending Moment

Testing the ideal send time depending on the customers’ profile and their behaviors is crucial for business differences and when preparing an email marketing campaign, the day and hour of newsletter distribution are regarded as key executive strategies [5]. Tuesday and Thursday are the most common business days to launch email marketing campaigns since most companies prefer to do it throughout the week [52].

According to a survey by MailChimp, sending emails throughout the week is preferable to doing so on the weekend. The worst day of the week to send newsletters is Friday, while the greatest day for email marketing is Thursday [53]. The information supplied by MailChimp about Saturday and Sunday as the days with the lowest newsletter opens has been confirmed by Hubspot surveys. The greatest day to send a newsletter, according to this survey, is Tuesday, with 20% more opens than the norm [54]. The findings by other researchers show that Monday has the highest income per email [4], while others found no appreciable variations in Tuesday and Wednesday’s email opening rates [6]. Some hotels feel the optimum day to deliver their newsletter is on the days when the website has the highest traffic [8].

According to research, 60% of emails are sent between 8 a.m. and 4 p.m., meaning that 40% of emails are sent “after hours” [5]. The optimal time to send newsletters, according to research done by MailChimp using an algorithm called “Send Time Optimization,” is 10 a.m. In general, sending newsletters in the morning as opposed to the afternoon is advised [53]. In this follow-up, tests from Hubspot confirm those from MailChimp and find that the optimal times to deliver newsletters are between 10 a.m. and 12 p.m. [54]. However, there were no appreciable changes in the opening rate at the time of submission in the experiments done by Biloš, Turkalj, and Kelić [6].

2.4.2. Email Subject Line

Due to the rise in spam, the subject line’s substance and wording are crucial in grabbing users’ attention [51]. The subject line must arouse the interest of the receiver and prompt them to open the email. Due to the prevalence of spam, the initial challenge is convincing the receiver to read the message rather than discard it, therefore the subject line of the email is crucial [5]. According to studies, 64% of recipients read emails based on the subject line [4], and under marketing theories, scarcity refers to a situation in which, ceteris paribus, the demand for a given good outweighs the supply of that good [55]. Limitations on an item’s availability may have a favorable impact on preferences and desires, influencing how consumers make decisions [56]. It is worth noting, however, that the very structure of the subject line is an imperative determinant in opening the email message [57].

One of the guiding principles of any persuasive strategy is scarcity. A given good or service’s appeal increases with decreasing availability [3]. Researchers assert that scarcity promotes hype, and email marketing campaigns have increasingly used this tactic [58]. The most successful marketing tactic, far more so than emphasizing differentiation from rivals, is to emphasize a product’s rarity [59]. In ceteris paribus circumstances, where demand for a certain good outweighs supply, this is what marketing theories refer to as a condition of scarcity [60]. Limitations placed on the availability of a specific item may encourage consumer decision-making by positively influencing preference and desire [56]. The most lucrative method, far more so than concentrating on differentiating from competitors, is to promote a product’s rarity [4,59] and the majority of readers examine the first four words of a newsletter before determining whether to open it [2]. The subject line is the initial point of contact with customers, thus it must be carefully prepared to stimulate email opening and improve campaign outcomes [9].

2.4.3. Personalization

Personalization often enhances click-through rates, but just 35% of email marketing is individualized [5]. Receivers are 22.2 percent more likely to click on personalized subject lines [4]. Personalization boosts the effectiveness of marketing campaigns, but it should always be based on the status of the consumer connection already in place [5]. However, it does not significantly increase the response rate to an email marketing campaign, according to studies by Kent and Brandal [61]. It is also important to know that in studies conducted at an Australian hotel, personalized emails were found to generate an increased unsubscribe rate from hotel email marketing campaigns over non-personalized emails [8]. Notably, when the match between the offer in the message and the recipients’ personal traits is not expressly justified by businesses, consumers exhibit personalization reactance in reaction to highly personalized messages [62].

Another contribution comes from Huang and Shyu [63], who stated that regularly personalized emails enhance the relationship between retailers and their customers, improve service quality, and stimulate customer loyalty. Murphy, Long, Holleran, and Esterly [16], on the other hand, conclude that if there is personalization and placement of appropriate content in the subject lines, emails are more likely to be read, and personalization is seen as a positive factor that leads to consideration of the campaign by the recipient [9]. It is also worth mentioning a more recent contribution by Almeida and Casais [64], in which it was proven that subject line personalization increases the open rate of emails. Guests greatly appreciate personalized treatment as they feel valued and it leads to a good customer experience [65]. In the hotel industry, it is important to build and create not merely a transactional relationship, but a personal relationship with hotel guests [66], and the same occurs in other industries [67].

2.4.4. Curiosity

“Curiosity is the first and most basic feeling we find in the human mind” as stated by Edward Burke. Curiosity is possibly the most significant emotion with a persuasive quality. It is believed that curiosity is what drives transformation. To convince others, you must first ascertain what piques their interest [15] (p. 122). In recent years, researchers have paid increasingly more attention to the arousal of emotions [68]. Curiosity is said to be a motivator for empathy and the awareness of various markets [69].

Humans are inherently curious, and this trait serves as the major driver of learning, knowledge seeking, and devotion to things such as buying things [70]. For instance, when the offer is first shown, the intention is not to convince the buyer to buy right away but rather to pique their interest to encourage them to open and examine the email [71]. A subject line that piques the reader’s interest can improve the effectiveness of email marketing efforts. The fundamental objective is to communicate clearly and succinctly rather than to wow with huge phrases [72]. Words typically pique the consumer’s interest, prompting them to look fast and continue reading the advertisement [72].

2.4.5. Sender

The sender is a crucial step in effective email marketing because the first thing a customer asks after getting an email is, “Who is this email from?” [5]. Typically, businesses include their name or their name and the term “newsletter” in the sender field [5] and they should avoid using “info@” generically, which wastes space and is frequently seen as trash email [9]. Previous studies have shown that there are elements associated with the sender that influence subscribers’ perceptions [73].

2.4.6. Authority Figure

An authority figure has greater persuasive power, according to Cialdini’s book, because their position and knowledge lend them more credibility as sources of guidance and opinion [74]. People are more likely to follow instructions from a higher authority [75]. Therefore, the capacity for communication and persuasion will be favorably influenced if the recipient acknowledges the existence of an authority figure [74]. According to recent studies, consumers are more likely to identify fraud when the sender’s perceived credibility is reduced [76]. Given that customers frequently only read certain communications, the sender’s reputation is crucial in getting them to view and read the message [77]. Therefore one can conclude that not verifying the sender’s dependability can harm consumers’ attitudes [77].

2.5. Hotel Industry and Its Relationship with Email Marketing

According to several surveys, the Internet is playing a bigger and bigger role in marketing and selling travel goods such as hotels [16]. Additionally, the number of travelers who plan and book their vacations these days without the assistance of middlemen is rising quickly [11]. As a result, and as a result of growing competition on various platforms, these circumstances have led to an increase in the significance of competitive advantages, making email marketing a very potent weapon and an advantage that is essential to the creation of direct relationships with clients [16]. This kind of marketing can be used by businesses as a technique to encourage both the attraction and retention of new clients [78], but also to increase conversions [79].

The capabilities of email make it possible to provide a unique and customized service that strengthens the identity of the brand or business and improves connection with current or potential clients [15] (p. 112). For instance, in this regard, hotels send newsletters to past visitors to urge a return visit and even to encourage increased use of the hotel’s amenities while they are there [8]. Due to their limited marketing budgets, hotels have actively sought out proactive and innovative e-placement methods to cut expenses [7]. The use of email marketing, a versatile and affordable medium that enables direct communication with guests and agencies/operators by increasing numbers of hotel businesses, fills this gap [8]. As stated by Yang, et al. [80], even though emails are often used in the hotel industry, little study has been done on them, adding that post-stay emails may be applied when creating customer loyalty strategies.

2.6. Metrics for Evaluating Results

For the successful implementation of email marketing, it is necessary, before the start of the campaign, to concretely establish the intended goals and appropriate metrics [2]. Metrics are extremely important because, through them, it is possible to assess how campaigns affect the results of a company [9]. In addition, with metrics one obtains the accuracy of the results achieved by the campaigns, understanding and improving marketing activities, allowing companies to increase the effectiveness of actions and measure ROI [6]. The metrics that are considered most important are [81] (p. 435): Delivery rate (percentage of delivered emails); Bounced rate (percentage of undelivered emails); Open rate (percentage of emails opened); Click-through rate or click rate; Number of forwarded emails; Number of email responses; ROI (return on investment); Number of shares; Database growth; and Conversion rate (email activity generated by the website). However, for Fariborzi and Zahedifard [9], the metrics that are considered to be most important are: Delivery Rate, Open Rate, and Clickthrough rate.

2.7. Determinants and Persuasion Factors That Influence Newsletter Open Rate

Sending moment, subject line, and sender are the three categories used to categorize the elements and determinants. The elements and determinants under examination are the following: day of sending, time of sending, scarcity, curiosity, personalization, and authoritative figure. The dependent variable is the open rate of the newsletters sent.

2.7.1. Day of Sending the Newsletter Test

The results of the earlier studies are rather inconsistent because the best and worst sending days vary considerably depending on the industry and target market. The worst sending weekday is Friday (with lower opening rates), whereas Tuesday and Thursday are often the greatest days to send. In contrast to weekend results, weekday results are more favorable. It is not possible to test the mailing of newsletters on the weekends in the company under study. To determine whether Tuesday and Thursday are the best sending days with the highest opening rates, the hypothesis was created. Studies’ findings regarding the day newsletters were sent are in

Table 1. Findings regarding the day newsletters were sent.

References	Most/ Less Favorable Days	Comparisons
Kiran and Kishore [4]	Monday/n.a.
Biloš, Turkalj, and Kelić [6]	n.a./n.a.	Tuesday and Wednesday show no differences
Davies and Khim [54]	Tuesday/Friday	Weekdays more favorable than weekends
Abrahams, Chaudhary and Deane [52]	Tuesday and Wednesday/n.a.
Foreman [53]	Thursday/Friday	Weekdays more favorable than weekends

.

2.7.2. Time of Sending the Newsletter Test

In general, prior research indicates that the ideal time to deliver newsletters is between 10 a.m. and noon. With the help of this study, one will determine whether distributing newsletters from the hotel industry in the morning results in greater opening rates. Findings from previous research are presented in

Table 2. Findings on the timing of sending the newsletters.

References	Most Favorable Sending Time
Foreman [53]	10:00 a.m.: morning time in preference to afternoon time
Biloš, Turkalj, and Kelić [6]	The time of sending does not generate significant changes
Davies and Khim [54]	Between 10:00 a.m. and 12:00 p.m.
Rice [82]	Between 10:00 a.m. and 12:00 p.m.

.

2.7.3. Email Subject Line—Scarcity Test

The results of earlier studies show that the idea of a limited supply of a particular good amplifies the effects of the appeal and the expectations in the consumer’s mind. Therefore, one wants to see if using the concept of scarcity increases newsletter campaign opening rates in the hotel industry. Study findings about scarcity are in

Table 3. Findings on the use of scarcity as a marketing ploy in newsletter subject lines.

References	Findings Concerning Scarcity	Effects
Guadagno and Cialdini [3]	The less available the more attractive a product is	Positives
Koch and Benlian [58]	Helps with the hype campaign	Positives
Amaldoss and Jain [59]	Most favorable persuasion strategy	Positives
Gierl and Huettl [83]	The positive effect of scarcity depends on the context and product suitability	Neutral

.

2.7.4. Email Subject Line—Personalization Test

Because the literature research reveals numerous outcomes, it is not possible to draw any conclusions from the earlier studies on whether a personalized subject line produces better results in email marketing efforts. The formulation of the hypothesis is aimed at testing if more personalized subject lines that include the recipient’s name result in higher open and clickthrough rates, especially in the hotel industry. Findings about personalized subject lines for newsletters are in

Table 4. Findings about personalized subject lines for newsletters.

References	Findings Concerning Personalization	Effects
Marinova, Murphy, and Massey [8]	Generic subject lines show better results.	Negative
Kiran and Kishore [4]	Custom subject lines are more likely to be opened.	Positive
Biloš, Turkalj, and Kelić [6]	Generic lines show better results.	Negative
Fariborzi and Zahedifard [9]	Subject line personalization increases open rates.	Positive
Ellis-Chadwick and Doherty [5]	It depends on the state of the relationship with the consumer.	Positive or negative
Ellis-Chadwick and Doherty [5]	Personalization generates an increased click-through rate	Positive
Murphy, Long, Holleran, and Esterly [16]	Personalization makes it easier to read emails.	Positive
Kent and Brandal [61]	Personalization does not generate significant results.	Negative

.

2.7.5. Email Subject Line—Curiosity Test

The literature under consideration reveals encouraging findings about the employment of an appeal to curiosity, as it sparks interest, ignites sympathy, and generates low-level commitment. In this way, one wants to see if increasing people’s interest improves email marketing campaigns in general and increases open rates.

Table 5. Findings concerning curiosity in the subject line of newsletters.

References	Findings Concerning Curiosity	Effects
Ogilvy [72]	Sparking the consumer’s interest leads to reading the rest of the ad.	Positive
Windahl [69]	Curiosity catalyzes empathy.	Positive
Wilson and Pettijohn [71]	Curiosity sparks low-level commitment.	Positive
Lakhani [15]	Curiosity is the engine of change and drives a recipient to action	Positive

contains the findings from studies related to curiosity.

2.7.6. Sender—Authority Figure Test

The literature research and the collection of studies conducted earlier led us to the conclusion that email marketing efforts are positively impacted by the sender’s authority. To investigate if a sender with a name that conveys greater authority generates better newsletter opening rates in the hotel business, this hypothesis was developed (

Table 6. Findings on the authority of newsletter senders.

References	Findings Concerning Authority	Effects
Cialdini [74]	Recognition of authority figure leads to greater persuasiveness	Positive
George, Tilley and Giordano [76]	The lower the credibility of the sender the greater the deception	Positive
Shareef, Dwivedi, Kumar, and Kumar [77]	The unreliability of the sender can have a negative impact	Positive

).

2.7.7. Hypothesis Formulation

Based on the literature reviewed and the results previously presented, it is now feasible to propose the following research hypotheses.

H1. 

Tuesday and Thursday are the most favorable days for sending newsletters with higher open rates.

H2. 

Morning hours are the most favorable for sending newsletters with higher open rates.

H3. 

Appealing to scarcity in the subject line generates higher newsletter open rates.

H4. 

Personalized subject lines generate higher newsletter open rates.

H5. 

Curiosity in the subject line generates higher newsletter open rates.

H6. 

A sender that conveys more authority generates higher newsletter open rates.

3. Materials and Methods

The company under investigation, this study’s goals, and the sample are all described in this section. There is also an introduction to the methodology, a detailed explanation of the data-gathering process, and a description of the steps that the empirical study will take. This study was conducted in a five-star hotel in a rural area in northern Portugal. The hotel caters to a wealthy clientele with high standards of quality who are always looking for the best and most cutting-edge deals. Given that these are wealthy clients, the marketing strategy is not centered on price penetration but rather on differentiating the experiences and services provided. When it comes to newsletter distribution, the hotel does not maintain a consistent schedule. However, throughout the holiday seasons (Christmas, New Year’s Eve, Carnival, Valentine’s Day, and Easter), email marketing efforts are always delivered.

3.1. Methodology

Evaluating the effect of the persuasive determinants of the newsletter opening is the foundation of the study and is the result of empirical recognition to comprehend and put into practice strategies that are meant to enhance email marketing campaigns in the hotel industry. Causal research was performed to determine if one event leads to another, or whether changes in one factor lead to changes in other factors [84]. When one aspect changes, it is important to look into whether a cause-and-effect relationship exists. Consider the sender, topic line, and sending moment determinants in this situation. Although causality is a powerful idea, there are drawbacks related to high expenditures and lengthy preparation times [84]. This research used an experiment-based study method, which involved testing variables under the control of certain circumstances to measure the effect of another variable [85].

The experiment was conducted in an ad hoc manner, without notifying the sample, to obtain responses from actual consumer behavior, to have true results, and to avoid bias [86]. This study was quantitative in nature and used test results to understand the current situation. It aims to quantify participant responses and then analyze the findings to help with decision-making [87]. Concerns exist regarding the objective assessment and quantification of data in these quantitative investigations. Quantitative research also concentrates on demonstrating or refuting the formulated hypotheses [87].

3.2. Data Collection

Using persuasive determinants related to the timing of sending, subject line, and authoritative sender, the research’s data collection aims to get values about open, click, unsubscribe, and bounced rates. Customers randomly got emails that may either be the control version (A) or the treatment version (B) in A/B experiments. This is how data was collected [87]. A/B testing involves making two distinct versions of the same campaign: the control version (A), which has the content and form that is typically sent, and the treatment version (B), which has been modified in some way to reflect the determinant or factor that you wish to analyze. Customers are randomly split into two equal parts and in the end, the segment that yields the best outcomes is determined [9].

This research was limited by the small size of the database because the hotel has a rather limited number of more than one hundred subscribers. Subscribers are customers of the hotel who have agreed to receive information by email. Therefore, the contacts to whom the newsletters will be sent will be separated into two equal parts and the varied subject lines, senders, and moments of sending will be examined, and conclusions will be drawn about the hypotheses made. Data were gathered for the study using experimental experiments and involved sending newsletters between October and March. Ten tests were run for each determinant (sender, subject line, and hour of sending day), and fifteen tests were run for the day of sending. The variables under study—the moment of sending (day and hour of sending), the subject line (curiosity, personalization, and scarcity), and the authoritative sender—were defined based on the literature review. One or more study hypotheses were assigned to each of the determinants. Following the A/B test methodology, experimental testing was conducted, consisting of sending emails in two distinct versions to further assess whether the hypotheses were confirmed. Information from MailChimp was used to determine whether the hypotheses have been validated, and information was collected on newsletter open rates.

4. Results

The findings from the empirical study are reported in this section. Data analysis is done in stages, with the first step comparing the means of the test A and test B outcomes. Then, statistical tests will be run to see if the groups exhibit statistically significant differences to confirm whether or not the hypotheses are rejected. It also includes a comparison of the findings with other research that has been previously published and reported. Non-parametric tests are used since they are appropriate for smaller samples and do not require conditions such as normality assumptions. The Mann–Whitney test is the most suitable non-parametric test for two independent samples. This allows for the comparison of the two groups of studied instances’ behavior to establish whether they are similar [88].

4.1. Testing on the Day of Sending the Newsletter

The same newsletter was used in both experiments to determine when to send the campaigns, however, test A and test B differed in that the first test was sent on Monday, Wednesday, or Friday while the second test was sent on Thursday or Tuesday. Ten experimental tests were then carried out to see whether Hypothesis 1 was validated (see Appendix A,

Table A1. Tests about the day of sending the newsletter.

Number	Test
1	Thursday
	Monday
2	Monday
	Tuesday
3	Monday
	Tuesday
4	Wednesday
	Thursday
5	Wednesday
	Thursday
6	Tuesday
	Friday
7	Thursday
	Friday
8	Tuesday
	Wednesday
9	Wednesday
	Thursday
10	Wednesday
	Thursday

). Recalling Hypothesis 1:

H1. 

Tuesday and Thursday are the most favorable days for sending newsletters with higher open rates.

Comparing the means, we can observe that test B has opening rates that are more than 1 percent points greater than test A, indicating that delivering newsletter campaigns on Tuesday and Thursday is preferable (

Table 7. Descriptive results regarding the day of sending the newsletter.

	Group		Statistics	Standard Error
Open	1	Mean	20.77%	2.47%
		Median	20.45%
		Standard Deviation	7.80%
	2	Mean	21.93%	2.26%
		Median	22.00%
		Standard Deviation	7.133%

). To validate or refute the hypothesis, we must first determine whether the groups exhibit statistically significant similarities. The Mann–Whitney test will be used for this.

It is required that the distributions of the two groups are equal before applying this non-parametric test. The variance homogeneity test and the normality test in this instance are used to confirm it. Since the significance of Levene’s test results is 0.665, which is higher than the threshold of 0.05, we can conclude that the variances in both groups are identical (

Table 8. Levene’s test regarding the day of sending the newsletter.

Test for Homogeneity of Variance or Levene’s Test
Levene Statistics	gl1	gl2	Sig.
0.194	1	18	0.665

).

Both distributions pass the normality test, as shown by the Shapiro–Wilk test findings, which have significant levels over 0.05 (open 1: sig. = 0.196 and open 2: sig. = 0.507) (

Table 9. Normality test relative to the day of sending of the newsletter.

Normality Tests
	Group	Kolmogorov–Smirnov a			Shapiro–Wilk
		Statistics	gl	Sig.	Statistics	Gl	Sig.
Open	1	0.227	10	0.153	0.896	10	0.196
	2	0.167	10	0.200 *	0.936	10	0.507

^a Lilliefors Significance Correlation; * This is a lower limit of true significance.

).

The distribution of groups 1 and 2 is normal, as shown by the results of the normality test and the variance homogeneity test. The Mann–Whitney test can then be used as a result.

Table 10. Mann–Whitney’s test about the day of sending the newsletter.

Test Statistics a
	Open	Click	Bounced	Unsubscribed
Mann–Whitney U	44.000	39.500	41.500	41.000
Wilcoxon W	99.000	94.500	96.500	96.000
Z	−0.454	−0.805	−0.680	−0.781
Significance Assint. (Bilateral)	0.650	0.421	0.496	0.435
Exact sig. [2 × (Sig. of one-sided)]	0.684 b	0.436 b	0.529 b	0.529 b

^a Grouping Variable: Group; ^b Not corrected for ties.

’s findings from the non-parametric test allow us to conclude that there are no statistically significant differences between the groups (U = 44; p > 0.05). We can therefore determine that, despite the previously observed means, there are no statistically significant variations between the campaigns’ Tuesday and Thursday deliveries, making it impossible to validate Hypothesis 1.

Thus, the findings of the empirical study did not support the results of Abrahams, Chaudhary and Deane [52], Biloš, Turkalj, and Kelić [6], Kiran and Kishore [4], as well as those of Foreman [53], and Davies and Khim [54], because the results show that the difference of sending on Tuesday and Thursday is not statistically significant compared with the other days of the week.

4.2. Testing on the Time of Sending the Newsletter

The same newsletter was used for the experiments regarding sending time. Here, the fact that test A was sent at a specific time in the morning (10 a.m. or 11 a.m.) and test B was delivered in the afternoon, distinguished test A from test B (2 p.m. or 5 p.m.). Ten experiments were performed (see Appendix A,

Table A2. Tests about the time of sending the newsletter.

Number	Test
1	Monday at 10:00 a.m.
	Monday at 2:00 p.m.
2	Friday at 10:00 a.m.
	Friday at 2:00 p.m.
3	Thursday at 10:00 a.m.
	Thursday at 2:00 p.m.
4	Thursday at 10:00 a.m.
	Thursday at 2:00 p.m.
5	Thursday at 10:00 a.m.
	Thursday at 2:00 p.m.
6	Thursday at 10:00 a.m.
	Thursday at 2:00 p.m.
7	Thursday at 10:00 a.m.
	Thursday at 2:00 p.m.
8	Monday at 10:00 a.m.
	Monday at 2:00 p.m.
9	Wednesday at 11:00 a.m.
	Wednesday at 17 h
10	Wednesday at 11:00 a.m.
	Wednesday at 17 h

). Recalling Hypothesis 2:

H2. 

Morning hours are the most favorable for sending newsletters with the highest open rate.

When comparing the means of the campaigns’ results, it was discovered that test A had an opening rate that was more than 1.5 percentage points greater than test B (

Table 11. Descriptive results about the day of sending the newsletter.

	Group		Statistics	Standard Error
Open	1	Mean	20.14%	2.94%
		Median	18.65%
		Standard Deviation	9.29%
	2	Mean	21.93%	2.26%
		Median	22.00%
		Standard Deviation	7.13%

). The statistical significance of the differences between the groups must be confirmed, though, and nonparametric tests were used.

The nonparametric Mann–Whitney test’s condition that the distributions of the two groups be equal must first be verified to use this test. For a type I error of 0.01, 0.05, and 0.10, Levene’s test with sig. = 0.806, presented in

Table 12. Levene’s test about the time of sending the newsletter.

Test for Homogeneity of Variance or Levene’s Test
Levene Statistics	gl1	gl2	Sig.
0.062	1	18	0.806

, reveals that the groups have the same distribution.

According to the Shapiro–Wilk test, one can say that group two’s distribution is normal (sig. = 0.795), whereas group one′s distribution is only normal for a p = 0.01 since sig. = 0.026 (

Table 13. Normality test relative to the time of sending the newsletter.

Normality Tests
	Group	Kolmogorov–Smirnov a			Shapiro–Wilk
		Statistics	gl	Sig.	Statistics	Gl	Sig.
Open	1	0.302	10	0.010	0.821	10	0.026
	2	0.180	10	0.200 *	0.961	10	0.795

^a Lilliefors Significance Correlation; * This is a lower limit of true significance.

).

The results of the nonparametric Mann–Whitney test, shown in

Table 14. Mann–Whitney’s test about the time of sending the newsletter.

Test Statistics a
	Open	Click	Bounced	Unsubscribed
Mann–Whitney U	47.500	47.000	42.500	50.000
Wilcoxon W	102.500	102.000	97.500	105.000
Z	−0.190	−0.239	−0.572	0.000
Significance Assint. (Bilateral)	0.850	0.811	0.567	1.000
Exact sig. [2 × (Sig. of one-sided)]	0.853 b	0.853 b	0.579 b	1.000 b

^a Grouping Variable: Group; ^b Not corrected for ties.

, indicate that there is no difference between the two distributions for type I errors of 0.01, 0.05, or 0.10. As a result, there is no statistically significant difference between the groups (U = 47.500; p > 0.05 and even though one has higher values in group one than in group two in the results comparing the means, this difference is not statistically significant.

The findings support research by Biloš, Turkalj, and Kelić [6], who found that when comparing the time of sending newsletters, there were no appreciable differences in the open rate. They do not, however, support the research results of Rice [82] that the ideal time to send email messages is between 10 a.m. and 12 p.m., nor the findings of studies done by Davies and Khim [54] and Foreman [53], which stated the hours between 10 a.m. and 12 p.m. are the optimum times to distribute emails.

4.3. Testing on the Scarcity Appeal of the Newsletter

Two variations of the same newsletter were used for each test, with test A serving as the control and using the standard hotel subject line (for example, Special Easter Offers) and test B introducing the variable under investigation, in this case, an allusion to scarcity (for example, “Book now, with limited availability!”). Ten tests using various phrases that allude to scarcity were run for this determinant (see Appendix A,

Table A3. Tests about the scarcity appeal.

Number	Test
1	Book now with limited availability!
	Special Offers from the Hotel!
2	Book now with limited availability!
	Special Offers from the Hotel!
3	Book now, with limited availability
	Hotel Special Program!
4	Special Offers limited availability
	Low Season Specials
5	Special Offers limited availability
	Low Season Specials
6	Special Offers with limited availability
	Low Season Specials
7	Special low season offers
	Limited availability special offers
8	Special low season offers
	Limited availability special offers
9	Special low season offers
	Limited availability special offers
10	Special low season offers
	Limited availability special offers

). Recalling Hypothesis 3:

H3. 

Appealing to scarcity in the subject line generates higher newsletter open rates.

Given the comparison of the means in

Table 15. Descriptive results about the scarcity appeal.

	Group		Statistics	Standard Error
Open	1	Mean	18.51%	1.78%
		Median	19.10%
		Standard Deviation	5.64%
	2	Mean	21.93%	2.26%
		Median	22.00%
		Standard Deviation	7.13%

, one can observe that test B had an average newsletter open rate that was 3.42 percent points greater than test A. These findings, however, are insufficient to refute or validate the hypothesis.

Then, as previously mentioned, the non-parametric Mann–Whitney test must be used to determine whether the findings of the groups show statistically significant differences. The test for homogeneity of variances and the normality confirm that the two groups have the same distributions. Since the significance level for the homogeneity of variances test is higher than 0.05 (sig. = 0.083), one may infer that the variances in both groups are equal (

Table 16. Levene’s test about the scarcity appeal.

Test for Homogeneity of Variance or Levene’s Test
Levene Statistics	gl1	gl2	Sig.
3.362	1	18	0.083

).

Since both distributions pass the Shapiro–Wilk test with results greater than 0.05, one can conclude that both are normal (

Table 17. Normality test about the scarcity appeal.

Normality Tests
	Group	Kolmogorov–Smirnov a			Shapiro–Wilk
		Statistics	gl	Sig.	Statistics	Gl	Sig.
Open	1	0.157	10	0.200 *	0.956	10	0.744
	2	0.295	10	0.014	0.855	10	0.066

^a Lilliefors Significance Correlation; * This is a lower limit of true significance.

).

We can infer from the results of the two tests that the distribution in groups one and two is normal. It is therefore reasonable to use the Mann–Whitney test, which demonstrates that the differences between the groups are not statistically significant (U = 43.000; p > 0.05) (

Table 18. Mann–Whitney’s test about the scarcity appeal.

Test Statistics a
	Open	Click	Bounced	Unsubscribed
Mann–Whitney U	43.000	37.500	46.000	41.000
Wilcoxon W	98.000	92.500	101.000	96.000
Z	−0.530	−1.067	−0.304	−0.841
Significance Assint. (Bilateral)	0.596	0.286	0.761	0.400
Exact sig. [2 × (Sig. of one-sided)]	0.631 b	0.353 b	0.796 b	0.529 b

^a Grouping Variable: Group; ^b Not corrected for ties.

). As a result, it is plausible to conclude that there are no statistically significant differences in the data obtained in the two groups, which contradicts Hypothesis 3.

The findings of the empirical research do not support the assertions made in the studies by Guadagno and Cialdini [3] that a product is more desirable the less readily available it is. The findings also do not support the assertion of Koch and Benlian [58] that the scarcity appeal raises expectations and, as a result, engagement in the campaign.

4.4. Testing on the Personalization of the Newsletter

Two variations of the newsletter were created for the personalization test; test A was a generic subject line (for instance, “Warm up your autumn with special deals”), while test B included the customer’s first name (“Maria, warm up your autumn with special offers”). Ten different experiments were performed for this determinant (see Appendix A,

Table A4. Tests about the personalized subject lines.

Number	Test
1	*|FNAME|*, warm up your autumn with special offers!
	Warm up your autumn with special offers!
2	*|FNAME|*, profitez de l’automne avec les offres spéciales!
	Profitez de l’automne avec les offres spéciales!
3	Special Hotel Program
	*|FNAME|*, the Hotel’s special program!
4	*|FNAME|*, el hotel tiene novedades de Navidad especiales!
	El hotel tiene novedades de Navidad especiales
5	*|FNAME|*, Découvrez les nouveautés de Noël!
	Découvrez les nouveautés de Noël!
6	The hotel has Christmas news specially for you
	*|FNAME|*, the hotel has Christmas news specially for you
7	*|FNAME|*, Don’t miss the special getaway offer!
	Don’t miss out on a special getaway offer!
8	*|FNAME|*, Don’t miss the special getaway offer!
	Don’t miss the special getaway offer!
9	*|FNAME|*, No pierda la oferta especial de escapada!
	No pierda la oferta especial de escapada!
10	*|FNAME|*, Ne manquez pas l’offre spéciale d’escapade!
	Ne manquez pas l’offre spéciale d’escapade!

). Recalling Hypothesis 4:

H4. 

Personalized subject line generates higher newsletter open rates.

The results obtained in terms of comparing means (

Table 19. Descriptive results about the personalized subject line.

	Group		Statistics	Standard Error
Open	1	Mean	28.92%	2.67%
		Median	31.85%
		Standard Deviation	8.44%
	2	Mean	28.78%	2.25%
		Median	30.20%
		Standard Deviation	7.12%

) do not demonstrate a significant difference between the values obtained in the two tests. The open rate difference between the generic and customized subject lines is merely 0.14 percent. A nonparametric Mann–Whitney test was used to determine whether the differences between the groups’ results are statistically significant.

It is required to confirm that the distribution of the two groups is equal before using this non-parametric test. Therefore, one employs the variance homogeneity test and the normality test. For a type I error of 0.01, 0.05, or 0.10, Levene’s test (

Table 20. Levene’s test about the personalized subject line.

Test for Homogeneity of Variance or Levene’s Test
Levene Statistics	gl1	gl2	Sig.
0.741	1	18	0.401

) with sig. = 0.401 demonstrates that the distributions have the same dispersion.

Shapiro–Wilk test results reveal that group one’s distribution is normal (sig. = 0.272), but group two’s distribution is only normal with a p-value of 0.01, with sig. = 0.029 (

Table 21. Normality test about the personalized subject line.

Normality Tests
	Group	Kolmogorov–Smirnov a			Shapiro–Wilk
		Statistics	Gl	Sig.	Statistics	Gl	Sig.
Open	1	0.220	10	0.186	0.909	10	0.272
	2	0.193	10	0.200 *	0.825	10	0.029

^a Lilliefors Significance Correlation; * This is a lower limit of true significance.

).

Since there are no statistically significant differences between the groups, according to the Mann–Whitney test, Hypothesis 4 cannot be validated (U = 49; p > 0.05) (

Table 22. Mann–Whitney’s test about the personalized subject line.

Test Statistics a
	Open	Click	Bounced	Unsubscribed
Mann–Whitney U	49.000	41.000	46.500	48.000
Wilcoxon W	104.000	96.000	101.500	103.000
Z	−0.076	−0.689	−0.265	−0.162
Significance Assint. (Bilateral)	0.940	0.491	0.791	0.871
Exact sig. [2 × (Sig. of one-sided)]	0.971 b	0.529 b	0.796 b	0.912 b

^a Grouping Variable: Group; ^b Not corrected for ties.

).

Personalization, as noted by writers Ellis-Chadwick and Doherty [5], can result in better marketing campaigns, but it should always be based on the condition of the already-existing connection with the customer. Upper-class customers for the company in the study might not value the personalization that comes with using their first name. Or using the name would be pointless given that email marketing campaigns are increasingly using personalization and seeing our name in the mailbox has become routine. Like the results obtained here, studies conducted by Kent and Brandal [61] concluded that the use of personalization does not show significant results in the open rate of outbound campaigns. We find that personalization is an irrelevant technique for improving results.

4.5. Testing on the Curiosity in the Newsletter

Two variations of the subject line were made for the 10 tests that were designed to use appeal to curiosity (see Appendix A,

Table A5. Tests about the curiosity appeal.

Number	Test
1	Enjoy the autumn with Special Offers!
	Have you seen our special offer?
2	Discover our Corporate Offers!
	Hotel Business Offer!
3	Discover our Corporate Offers!
	Hotel Business Offering
4	Découvrez le Programme Spécial!
	Programme Spécial de l’hôtel
5	Give the ideal Christmas gift!
	Discover the ideal Christmas gift
6	Ofertas especiales de Pascua!
	¡Sorpréndase con las ofertas especiales de Pascua!
7	Offres spéciales de Pâques!
	Découvrez les offres spéciales!
8	Easter special offers!
	Be amazed by our Easter special offers!
9	Offres spéciales de l’hòtel!
	Découvrez les offres spéciales!
10	Ofertas especiales de l’hôtel!
	¡Sorpréndase con las ofertas especiales!

). One for test A, the control (e.g., “Special Offers”), and the other for test B, to stimulate the recipient’s interest (For example, “Discover Special Offers”). Recalling Hypothesis 5:

H5. 

Curiosity in the subject line generates higher newsletter open rates.

Regarding the means, the campaign results enable us to confirm that there was little variation in the open rate between the two lines tested in terms of values attained. The open rates obtained in the experiments with subject line B, which appeals to curiosity (

Table 23. Descriptive results about the curiosity in the subject line.

	Group		Statistics	Standard Error
Open	1	Mean	23.96%	3.65%
		Median	26.55%
		Standard Deviation	11.56%
	2	Mean	24.91%	3.01%
		Median	27.25%
		Standard Deviation	9.52%

), were less than one percent greater than with line A. Applying a non-parametric test to see if the groups where the tests are being run exhibit statistically significant differences will help determine whether the results are reliable. This was determined using the Mann–Whitney test.

The two groups’ distributions had to match for this non-parametric test to be used. Two tests were performed for this: one for normality and the other for the homogeneity of variances. We confirmed that the Levene test’s significance is greater than 0.05, and we may infer that the variances in the two groups are equal (sig. = 0.280) (

Table 24. Levene’s test about the curiosity in the subject line.

Test for Homogeneity of Variance or Levene’s Test
Levene Statistics	gl1	gl2	Sig.
1.240	1	18	0.280

).

The normality test, more specifically the Shapiro–Wilk test, allows us to conclude that the distribution in the two groups is normal because the significance is greater than 0.05 (group 1: sig. = 0.202 and group 1: sig. = 0.533) (

Table 25. Normality test about the curiosity in the subject line.

Normality Tests
	Group	Kolmogorov-Smirnov a			Shapiro-Wilk
		Statistics	gl	Sig.	Statistics	gl	Sig.
Open	1	0.220	10	0.188	0.897	10	0.202
	2	0.204	10	0.200 *	0.938	10	0.533

^a Lilliefors Significance Correlation; * This is a lower limit of true significance.

).

It is possible to infer that group one and group two’s distributions are normal from the results of the Levene and Shapiro–Wilk tests. The Mann–Whitney test can be used in this situation. The findings of this non-parametric test allow us to conclude that there are no statistically significant differences between the groups (1 and 2) (U = 47; p > 0.05) (

Table 26. Mann–Whitney’s test about the curiosity in the subject line.

Test Statistics a
	Open	Click	Bounced	Unsubscribed
Mann–Whitney U	47.000	41.500	43.000	40.000
Wilcoxon W	102.000	96.500	98.000	95.000
Z	−0.227	−0.649	−0.568	−0.816
Significance Assint. (Bilateral)	0.821	0.517	0.570	0.414
Exact sig. [2 × (Sig. of one-sided)]	0.853 b	0.529 b	0.631 b	0.481 b

^a Grouping Variable: Group; ^b Not corrected for ties.

), which means that Hypothesis 5 is not supported.

We can infer that the subject line’s ability to pique the reader’s interest did not lead to an improvement in email marketing campaign outcomes. Given that academics have recently begun to pay more attention to curiosity, more impactful results with more significance were anticipated [68]. Its primary objective is not to encourage the customer to make the purchase right away, but rather to pique curiosity to establish a low level of engagement that favors the opening and viewing of the email [15,69,71].

4.6. Testing on the Sender Authority in the Newsletter

The newsletters were the same in the test on the sender authority and were developed in a generic manner similar to how the hotel often sent them. However, in test A the sender was the firm name, whereas in test B the sender was an authority figure, the director’s name, and his title. Ten experimental tests were run for this determinant (see Appendix A,

Table A6. Tests about the authority figure.

Number	Test
1	Hotel name
	Name of the Hotel Director|Owner and Manager
2	Hotel name
	Name of the Hotel Director|Owner and Manager
3	Hotel name
	Name of the Hotel Director|Owner and Manager
4	Name of the Hotel Director|Owner and Manager
	Hotel name
5	Name of the Hotel Director|Owner and Manager
	Hotel name
6	Name of the Hotel Director|Owner and Manager
	Hotel name
7	Name of the Hotel Director|Owner and Manager
	Hotel name
8	Name of the Hotel Director|Owner and Manager
	Hotel name
9	Name of the Hotel Director|Owner and Manager
	Hotel name
10	Name of the Hotel Director|Owner and Manager
	Hotel name

). Recalling Hypothesis 6:

H6. 

A sender that conveys more authority generates higher newsletter open rates.

Comparing the means, the open rate indicates that test B performed 2.58 percent points better than test A (

Table 27. Descriptive results about the sender authority.

	Group		Statistics	Standard Error
Open	1	Mean	21.32%	3.49%
		Median	18.20%
		Standard Deviation	11.034%
	2	Mean	23.90%	4.37%
		Median	25.70%
		Standard Deviation	13.81%

). To validate or reject the hypothesis, it is required to determine whether the groups exhibit statistically significant differences. The non-parametric Mann–Whitney test is used for this.

The distributions of group one and group two must be confirmed to be equal before using this non-parametric test. The homogeneity of variances test and the normality test are used for this. Since the results of the homogeneity of variances test have a significance level above 0.05 (sig. = 0.517), we can confirm that the variances of the groups are equal (

Table 28. Levene’s test about the sender authority.

Test for Homogeneity of Variance or Levene’s Test
Levene Statistics	gl1	gl2	Sig.
0.436	1	18	0.517

).

The significance found in groups one and two for the values from the Shapiro–Wilk test was 0.165 and 0.066, respectively (

Table 29. Normality test about the sender authority.

Normality Tests
	Group	Kolmogorov-Smirnov a			Shapiro-Wilk
		Statistics	Gl	Sig.	Statistics	gl	Sig.
Open	1	0.217	10	0.199	0.889	10	0.165
	2	0.168	10	0.200 *	0.971	10	0.904

^a Lilliefors Significance Correlation; * This is a lower limit of true significance.

). Since both numbers are greater than 0.05, we may say that the groups’ distributions are normal.

We can conclude that group one and group two have the same distribution based on the results of the two tests. Therefore, the non-parametric test can be used and confirm that there are no statistically significant differences between groups one and two, based on the Mann–Whitney test results (U = 44.00 and p > 0.05) (

Table 30. Mann–Whitney’s test about the sender authority.

Test Statistics a
	Open	Click	Bounced	Unsubscribed
Mann–Whitney U	44.000	38.000	44.500	40.500
Wilcoxon W	99.000	93.000	99.500	95.500
Z	−0.454	−0.969	−0.417	−0.849
Significance Assint. (Bilateral)	0.650	0.332	0.677	0.396
Exact sig. [2 × (Sig. of one-sided)]	0.684 b	0.393 b	0.684 b	0.481 b

^a Grouping Variable: Group; ^b Not corrected for ties.

).

Overall, since there were no statistically significant changes between the groups, the findings do not support Hypothesis 6 that a sender with greater authority causes a rise in newsletter open rates. The findings contradict those of author Cialdini [74], who holds that an authority figure has higher persuasive power since one’s position and knowledge make one seem like a more reliable source of information and ideas. It also contradicts the research of Blass [75], who acknowledges that people are more inclined to follow instructions from an authority figure, and the works of George, Tilley, and Giordano [76] and Shareef, Dwivedi, Kumar, and Kumar [77].

5. Discussion and Conclusions

The examination of persuasion strategies as determinants that improve newsletter opening rates is covered in this research, with a particular emphasis on the hotel industry. That is, this study put a lot of emphasis on persuasion strategies that affect the outcomes of campaigns. Some results about the determinants (time of sending and day of sending) and persuasive elements were made through the empirical study done in a hotel in a rural setting in northern Portugal (personalization, curiosity, authority sender, and scarcity). Each determinant underwent at least ten tests.

Given the findings of the tests conducted on each persuasion determinant, it is not possible to conclude that mailing campaigns delivered in the morning produce greater results than those sent in the afternoon. Similar to the findings of the experiments on the sending day, it was unable to prove that email marketing campaigns performed better on Tuesday and Thursday. It is advised that the business do an internal study to identify the most effective days and hours for sending newsletters to each market.

It was found that the experiments with scarcity appeal did not result in a rise in the rate of newsletter openings. In this instance, the hotel’s ideal client is a wealthy individual who values an exceptional experience and is willing to pay a premium for it. Therefore, this could be a component that explains why campaigns that appeal to scarcity have less successful outcomes.

Personalization is a characteristic that many businesses employ in email marketing campaigns, but regrettably, it is no longer useful for enhancing campaign outcomes. The consumer is already accustomed to seeing his or her name in the email inbox, therefore this does not provoke a stronger response. Other studies have shown that personalization only produces favorable outcomes when there is a good relationship between the business and the client. Since the customers belong to the upper class, they may not appreciate having their first name used.

An element that can jeopardize the business is the use of tactics based on curiosity. Currently, the use of curiosity as a selling point is known as clickbait, a derogatory term for a widespread strategy used by businesses to generate more clicks and openings. As a result, while utilizing this strategy, it is crucial to establish a subject line that authentically piques interest and matches the content of the email to build a long-lasting relationship based on trust with the reader. One has to remember that the goal of a campaign is to generate sales and establish a lasting relationship with the consumer, not just to get people to open your newsletter. However, curiosity did not improve the performance of the newsletter when evaluated on the open rate metric.

Finally, presenting an authority figure did not improve the outcomes. This determinant did not result in higher interest from hotel guests. Typically, the presence of an authoritative figure contributes to persuasion and a better perception that the campaign is trustworthy, communicating security to customers when they click and open the message. All database subscribers have stayed at the hotel, so they are already familiar with the name and always identify it with the perception of the hotel, which allows us to justify this element.

“What is the influence of persuasive strategies as determinants of opening a newsletter in the hotel industry?” was the primary research question. We can infer that the tested strategies and specific determinants did not produce statistically significant results for this hotel. The novelty of the results of this study is its total opposition to what was collected in the literature review, which generally emphasizes that the determinants studied increase the open rate of newsletters. This is an important contribution to the study of email marketing. In view of the results obtained, in total contrast to what is stated in the literature, it is unequivocal that future research is necessary and desirable to confirm whether the determinants have an influence on the newsletters’ opening rate. This should be done systematically in various sectors, periods, and with larger samples.

The following inferences, it should be unequivocally emphasized, are limitations of the research conducted. The results obtained are the outcome of experimentation in a specific segment—a hotel in a higher market segment. This suggests that hotel units carry out tests within their email marketing campaigns, as the recommendations resulting from the literature review did not imply an increase in the newsletter opening rate. Even in the face of adverse results, in stark contrast to the bibliography reviewed, email remains a sustainable and effective alternative as a digital communication channel for the hotel industry.