Author(s): Albérico Travassos Rosário, GOVCOPP, IADE - Universidade Europeia, Portugal
作者： Albérico Travassos Rosário， GOVCOPP， IADE - 欧洲大学，葡萄牙

INTRODUCTION  介绍

Companies use email marketing to directly promote their products and services to potential clients using email. The popularity of email marketing can be linked to the development and acquisition of mobile technologies and the internet. GhavamiLahiji (2016) identifies three types of emails used for marketing, including direct emails, email newsletters, and transactional emails. The kind of email chosen depends on the targeted consumer population and the objectives of the marketing campaign. Compared to direct mail campaigns, email marketing is cheaper and faster. Zhang et al. (2017) indicate that an email campaign targeting 50000 people can take 6 hours to plan and execute, while direct mail campaign targets the same consumer size can take 17 days. The increased efficiency increases return in investment (ROI), making it an attractive marketing channel. Although email marketing investment is significantly lower than other methods such as TV and print ads and internet marketing , Wu et al. (2018) estimate that email marketing's ROI is high at 4325%. The high achievement can be attributed to increased interactions with consumers and faster responses, either manual or automatic.
公司使用电子邮件营销 通过电子邮件直接 向 潜在客户推广他们的产品和服务 。 电子邮件营销 的流行与 移动技术和互联网的开发和 收购有关。 GhavamiLahiji （2016） 确定了 三种用于营销的电子邮件 类型，包括直接电子邮件、电子邮件通讯和交易电子邮件。 选择 的电子邮件类型取决于 目标消费者群体和营销活动的目标。 与直邮活动相比，电子邮件营销更便宜 、更快捷。 Zhang 等人。 （2017） 表明， 针对 50000 人的电子邮件营销活动 可能需要 6 小时来规划和执行，而直邮营销活动针对相同的消费者规模 可能需要 17 天。 效率的提高 提高了 投资回报率 （ROI），使其成为 一个有吸引力的营销渠道。 尽管电子邮件营销投资 明显 低于 电视和平面广告以及互联网营销等其他方法，但 Wu 等人。 （2018） 估计 电子邮件营销的投资回报率 高达 4325%。 这一高成就可 归因于与消费者互动的增加 和更快的响应，无论是手动还是自动。

Email marketing enables marketers to share more information about a company and its products and services. The marketing channel allows additional information sources such as hyperlinks to the company websites, videos, and photos. Budac (2016) recommends that marketers create relevant content that creates curiosity and encourages users to follow the call to action, including links to additional information sources. The clarity of the marketing message, frequency of emails, and call-to-actions can influence consumers' interactions with marketing emails. According to Jeshurun (2018), an effective email marketing strategy should involve frequency and content planning, using a spam-free distribution system, creative content development, tracking, analysis, and reporting techniques. These aspects enable marketers to integrate long-term marketing goals by creating and deploying content that builds and strengthens company-consumer relationships and helps track the campaign's performance for consistent improvements.

This research paper aims to identify and synthesize literature on the effectiveness of email marketing and potential challenges affecting its proper implementation.

METHODOLOGICAL APPROACH

Systematic Bibliometric Literature Review (LRSB) methodology is a systematic process of collecting and synthesizing data to develop knowledge. Snyder (2019) explains that literature review involves integrating perspectives and findings from multiple empirical studies, giving the methodology more power than single studies. This method's primary purpose is to build the research and relate it to existing academic knowledge to create a firm foundation for advancing knowledge and facilitating theory development.

This article uses an LRSB to summarize and access current knowledge about email marketing as valuable research (Rosário, 2021, Rosário et al., 2021; Rosário, Raimundo, et al., 2021; Rosário & Cuz, 2019; Sacavém, et al., 2019).

Thus, we proceeded as follows: (i) definition of the research question; (ii) location of the studies; (iii) selection and evaluation of the studies; (iv) analysis and synthesis; (v) presentation of the results; and (vi) discussion and conclusion of the results. This methodology ensures that the review is comprehensive, auditable and replicable and answers the research question (Rosário, 2021, Rosário et al., 2021; Rosário, Raimundo, et al., 2021; Rosário & Cuz, 2019; Sacavém, et al., 2019). However, it is considered that the research has as a limitation to consider only the SCOPUS database, excluding the other academic bases.

This method's primary purpose is to build the research and relate it to existing academic knowledge to create a firm foundation for advancing knowledge and facilitating theory development. Therefore, using the literature review methodology for this research will enable data gathering and synthesis to identify evidence on email marketing's effectiveness and potential challenges and knowledge gaps affecting its implementation and outcomes.

The database of scientific articles used was SCOPUS, the most important peer-reviewed peer in the academic world. However, we consider that the study has the limitation of considering only the SCOPUS database, excluding the other academic bases. The literature search includes peer-reviewed scientific articles published until February 2021. The literature search was limited to the subject area "business, management and accounting" with "email marketing" as the specific keyword. Other search terms used include email marketing campaigns, responsive emails, email, marketing, and email advertising . The inclusion criteria involved (Table 1) a thorough screening divided into two stages, i.e., abstract screening and full-text screening. The process enabled narrowing down the number of potential sources identified during the initial search (N=351) to ensure only the most relevant sources were used (N=49).

Table 1.

Screening Methodology

Source: Own elaboration

PUBLICATION DISTRIBUTION

Peer-reviewed articles on the topic will be screened in the 2000-2021 period. 2010 and was the year with the highest number of peer-reviewed articles on the subject, reaching 6. Figure 1 summarizes the published peer-reviewed literature for the 2000-2021 period.

The publications were sorted out as follows: Printing Impressions (6); Journal Of Marketing Channels (4); European Journal Of Marketing (2); Instant And Small Commercial Printer (2); Journal Of Digital And Social Media Marketing (2); with a publication (Asia Pacific Journal Of Marketing And Logistics; Asian Journal Of Business Research; Australasian Marketing Journal; Baltic Journal Of Management; Cornell Hospitality Quarterly; Cornell Hotel And Restaurant Administration Quarterly; Cuadernos De Gestion; Drapers; Electronic Markets; Geographica Pannonica; Industrial Marketing Management; International Journal Of Electronic Commerce; International Journal Of Electronic Customer Relationship Management; International Journal Of Electronic Marketing And Retailing; International Journal Of Internet Marketing And Advertising; International Journal Of Sport Management And Marketing; Journal Of Business Research; Journal Of Current Issues And Research In Advertising; Journal Of Fashion Marketing And Management; Journal Of Global Information Management; Journal Of Interactive Marketing; Journal Of Internet Banking And Commerce; Journal Of Marketing; Journal Of Marketing Research; Journal Of Product Brand Management; Journal Of Promotion Management; Journal Of Retail And Leisure Property; Managerial And Decision Economics; Market Trziste; Marketing Science; Nonwovens Industry; PC World San Francisco CA; Technological Forecasting And Social Change).

Figure 1. Documents by year (Source: own elaboration)

In Table 2 we analyze for the Scimago Journal & Country Rank (SJR), the best quartile and the H index by publication. The Journal Of Marketing is the most quoted publication with 8,630 (SJR), Q1 and H index 233. There is a total of 14 journals on Q1, 6 journals on Q2 and 6 journals, Q3 and 8 journal on Q4. Journals from best quartile Q1 represent 37% of the 38 journals titles; best quartile Q2 represents 16%, best quartile Q3 represents 16%, best Q4 represents 11% and finally, 4 publications have no data representing 11% of a total of 38 publications.

As evident from Table 2, the significant majority of articles on email marketing rank on the Q1 best quartile index.

Table 2.

Scimago journal and country rank impact factor

Note: *data not available.

Source: Own elaboration.

The subject areas covered by the 66 scientific articles were: Business, Management and Accounting (49); Engineering (8); Economics, Econometrics and Finance (7); Computer Science (4); Social Sciences (4); Decision Sciences (3); Earth and Planetary Sciences (1); Materials Science (1); and Psychology (1).

The most quoted article was "From social to sale: The effects of firm-generated content in social media on customer behavior" from Kumar et al. (2016) with 284 quotes published in the Journal of Marketing 8,630 (SJR), the best quartile (Q1) and with H index (233). The published article focuses on study is to examine the effect of firm-generated content in social media on three key customer metrics: spending, cross-buying, and customer profitability.

In Figure 2 we can analyze the evolution of citations of articles published between 2010 and 2021. The number of quotes shows a positive net growth with an R2 of 34% for the period 2010-2021, with 2020 reaching 191 citations.

Figure 2. Evolution of citations between 2010 and 2021 (Source: Own elaboration)

The h-index was used to ascertain the productivity and impact of the published work, based on the largest number of articles included that had at least the same number of citations. Of the documents considered for the h-index, 17 have been cited at least 17 times.

In Appendix A, the citations of all scientific articles from the â¤2010 to 2021 period are analyzed; 15 documents were not cited until February 2021.

Appendix B examines the self-citation of the document during the period â¤2010 to 2021, the documents were self-cited 28 times, the article From social to sale: The effects of firm-generated content in social media on customer behavior by Kumar et al. (2018), published in the Journal of Marketing and Modeling customer opt-in and opt-out in a permission-based marketing context by Kumar et al. (2014) published in the Journal of Marketing Research were cited 7 times each.

In Figure 3, a bibliometric study was carried out to investigate and identify indicators on the dynamics and evolution of scientific information using the main keywords. The study of bibliometric results using the scientific software VOSviewe, aims at identifying the main research keywords email marketing campaign, email marketing.

The research was based upon the studied articles on Sports marketing and Sponsorship. The linked keywords can be examined in Figure 4 making it possible to make clear the network of keywords that appear together/linked in each scientific article, allowing to know the topics studied by the researches and to identify future research trends . In Figure 5, it is presented a profusion of bibliographic coupling with a unit of analysis of cited references.

Figure 3. Network of all keywords

Figure 4. Network of Linked Keywords

Figure 5. Network of bibliographic coupling

THEORETICAL PERSPECTIVES

The evolution of new media has led to constant development of digital marketing strategies, such as email marketing. Marketers use it to attract new customers and maintain existing ones through targeted and customized communication. BiloÅ¡a et al. (2016) rank email as one of the widely used electronic messaging applications globally and identify it as a ubiquitous business communication method. Organizations use emails as marketing channels to communicate their organizational value to potential and existing customers and for customers to interact with the companies (Multi-solutions evolution, 2008). However, Bonfrer and Drèze (2009) noted that response to email marketing messages has been declining in recent years, creating the need for marketers to evaluate their content and presentation to increase click rates. Clarke III et al. (2005) note that 85% of marketers use emails to communicate with existing customers, while 67% engages potential customers directly. However, only 29% of customers use emails to purchase online, and 24% to enquire about inventory (Dysart, 2000). These statistics indicate the need for increased efforts to boost consumer response rate and interactions with email marketing messages. Marketers need to evaluate the strengths and weaknesses of the email content and the target audience before deploying the emails and implement performance tracking technologies to increase outcomes.

THE EFFECTIVENESS OF EMAIL MARKETING

Email marketing is an ideal strategy for companies determined to build and maintain close relationships with their customers. Organizations use the marketing channel to communicate their value propositions while customers use it for inquiries. BiloÅ¡a et al. (2016) identify low costs, customization, users' segmentation, and measurability as the leading causes of its efficiency. Marketers utilize the digital environment's opportunities, such as analytical models, to assess weaknesses, strengths, and assumptions (Dysart, 2000). The evaluation enables data gathering to personalize email content and identify target markets to increase outcomes. Bonfrer and Drèze (2009) recommend using an email testing methodology where emails are sent to a sample population before the campaign begins to evaluate performance and identify areas needing improvement. These processes can help marketers overcome the emerging challenge of increasing the effectiveness and competitiveness of email marketing amidst newer strategies, such as internet and influencer marketing.

Email marketing has a higher ROI than other marketing strategies. Ellis-Chadwick and Doherty (2012) estimate that the ROI for email marketing campaigns twice the ROI of different techniques such as online directory ads and web banners. The high returns are linked to the low distribution and planning costs involved in email marketing and market segmentation , ensuring that the message is deployed to customers with a higher probability of clicking (Multi-solutions evolution, 2008). Clarke III et al. (2005) reported that 78% of consumers listed email as their preferred contact method, indicating the probability of using the technique to communicate with salespersons. However, research by Balasudarsun et al. (2018) revealed that 87% of participants preferred Chatbot marketing over Email Marketing. Chatbot Messenger is a marketing platform developed by Facebook that utilizes conversational intelligence to respond to consumer queries. Despite email marketing's higher ROI, the emergence of new developments such as artificial intelligence requires consistent improvement to match their pace and address target consumers' needs and demands.

Marketers can increase the effectiveness of email marketing through improved linguistic style and visual appeal. Ellis-Chadwick and Doherty (2012) indicate that the layout, length, and size of advertisements significantly influence audiences' attention and interests. Such executional strategies can increase click through rates and sales since they create recipient's curiosity (Lorente-Páramo et al. 2020). Dapko and Artis (2014) define visual appeal as the extent to which graphical elements such as font colors and pictures are incorporated in a message. Effective email marketing should include relevant photos and graphic images to enhance recipients' impressions (VDP drives cross-media, 2007). Balasudarsun et al. (2018) reported that consumers think pictures, videos, daily updates, emojis, GIFs, small talks, and FAQs are the most critical online marketing features. Therefore, an email marketing campaign's effectiveness depends on the creativity used to design the marketing message's visual aspects.

The linguistic style involves using informal and formal tone in marketing communication, which is depicted through different use of punctuation marks and language. Marketers use casual linguistic styles when communicating with existing customers by using expressive punctuations, such as exclamation marks, to make it conversational (Dapko & Artis, 2014). However, interactions with new customers require formal language, replacing the exclamation marks with periods (Perry & Shao, 2002). In established relationships, marketers and consumers have interacted multiple times, creating a sense of familiarity (Cagle, 2010). On the contrary, in a new relationship, the communicating parties are yet to understand each other's personalities, likes, and dislikes. Biloša et al. (2016) emphasize this aspect by indicating that message elements can directly influence the target audiences' reception of the distributed information. Although there are no standardized email marketing tactics, companies should ensure the message deployed accounts for differences in consumers' judgments (Perry & Shao, 2002). The consequences of miscommunication can be avoided by sharing proper messages aimed to build and strengthen relationships.

Additionally, an effective email marketing campaign should be spam-free. Clarke III et al. (2005) define spam as "unwanted email solicitations" and a primary concern in using email as a business communication strategy. The increased growth of spam mails has led to the establishment of stricter regulating measures, such as the CAN-SPAM Act of 2003 implemented in the US to offer a federal framework for regulating email. The actions aim to reduce the illegal schemes implemented to con people and make fast money. Jeshurun (2018) recommended that organizations and marketers should regulate transmission frequency to ensure that emails are only sent when something newsworthy occurs. Regulated spam-free emails can increase response rate since it builds trust and strengthens relationships with existing and potential customers.

PERMISSION-BASED EMAIL MARKETING

Permission-based emails were adopted as a response to increased consumer complaints regarding unsolicited emails. Organizations and marketers using these emails require recipients to provide consent and give them an opportunity to opt-in or opt-out to the emailing list (Marinova et al., 2002). Since consumers can choose firms they want to receive direct emails from, the probability of reading and clicking the provided additional sources is higher (Ellis-Chadwick & Doherty, 2012). Permission-based email marketing ensures that consumers only receive content that matches their interests and reduces junk emails. Marketers' effort to ask for customers' permission before sending promotional messages can influence their impressions, leading to positive behavior such as loyalty and willingness to purchase from the marketed brand (Cagle, 2010). Email marketing is a type of relationship marketing where firms focus on constant communication to build and maintain relationships with existing and potential customers. Therefore, valuing their consent can influence how they perceive the company and increase interactions with the marketing communication message.

Permission-based marketing creates a two-way communication platform to increase engagement and enhance interactions. Traditionally, consumers were recipients of marketing communication with limited opportunity to interact with marketers and firms (Cagle, 2011). However, permission-based marketing enables them to interact with the deployed promotional message and share feedback with the marketers and companies (Biloša et al., 2016). The recipients' consent to receiving marketing messages, allowing the firm to add their email addresses to the organizational database for frequent updates (Greenbaum, 2011). The connection created improves customer relationship management since firms understand how their customers respond to firm-generated marketing content (Kumar et al., 2016). The capability to directly communicate with a firm, whether for inquiries, present complaints, or place orders, increases customers' perceived worth- since they feel valued (Dysart, 2010). However, the success of the two-way communication function of the marketing strategy depends on the marketers' capability to reply to consumers' emails on time and with appropriate information to avoid negative emotions such as frustrations and anger.

Additionally, permission-based marketing enables targeting specific market segments, increasing outcomes. Klenosky and Brey (2010) explain that when creating email marketing campaigns, markers should consider the market segments or consumer subgroups that would be interested in receiving the messages, frequency of deployment, type of information, formatting, and the use of multimedia. These aspects highlight the need to develop consumer profiles to ensure that the targeted groups' interests match the promotional messages relayed (Cagle, 2011). Lin et al. (2015) emphasize this point by indicating that the purpose of permission-based email marketing is to satisfy customer needs by ensuring the information they receive is directly related to them and their passions and concerns. Marinova et al. (2002) further explain that understanding consumers, their preferences, buying behaviors, and future purchasing motives is a critical component of customer relationship management. In permission-based email marketing, these goals are achieved by analyzing customer-based databases to create a target list and buyers profiles (Dysart, 2010). Unsolicited emails can increase consumer suspicions about a company's motives, leading to lower interactions with the promotional messages. However, customer profiling aided by data consented to by the target audiences can reduce spam reports and customer displeasures. Segmentation ensures that accurate information is sent to a particular group of people within a specific time, fostering customer relations.

Permission-based email marketing increases the probability of success and decreases the mailing volume. Lin et al. (2015) indicate that untargeted promotional emails increase social costs and resource wastage since the bulk emails are sent to people whose interests do not match the company's products or services. The likelihood of opening or reading these emails is low, causing higher costs and waste of time and resources (Spear, 2008). Therefore, permission-based marketing can be identified as a solution to the problem since the emails are only sent to consumers who have allowed marketers to share them (Marinova et al., 2002). These customers receive information on products, services, and special sales and offers (Greenbaum, 2011). Consenting indicates that the client is aware of the organization or brand and is interested in its information, increasing the probability of reading the emails and clicking on other shared additional information sources such as hyperlinks.

Permission marketing creates long-lasting relationships with customers. Marinova et al. (2002) explain that acquiring customer consent and analyzing their data for customization involves a long process where both parties invest time, resources, and information. The investment results in an interactive and active relationship characterized by two-way communication in a virtual world (Greenbaum, 2010). Reimers et al. (2016) note that emails provide quick and convenient communication solutions since the interactions occur in real-time. In such situations, the customers are likely to expand the levels of permission granted to marketers due to increased trust. Marinova et al. (2002) identify five levels of consent given to a company by its targeted consumers; intravenous, points, personal relationship, brand trust, and situation. Situation permission occurs when customers grant a company limited or one-time permission. The promotional messages can only be sent for a specified duration (Spear, 2008). Under 'brand trust' permission level, consent to promotional messages occurs when the targeted consumer develops confidence in a brand and the marketer. The faith leads to individual relationships in the third level to influence consumer behaviors through customization. The points-permission level, occurs when email recipients grant companies access to personal information to facilitate points-based loyalty programs for frequent customers. Intravenous is the topmost permission level that occurs after the consumer has substantial understanding of the brand and trust to allow salespeople to make buying decisions on their behalf. Permission-based email marketing campaigns should strive to achieve the final goal since it leads to customer retention, which Reimers et al. (2016) identify as a fundamental goal of online business practices. Ultimately, permission-based email marketing's effectiveness is to develop target lists from customer information to initiate email marketing campaigns that capture the target population's interests. It helps reduce promotional clutter that has been undermining the effectiveness of online advertising strategies. The development of the consumer-organization relationship can be further analyzed using the hierarchy-of-effects theory, which identifies the interactions as a journey that progresses through different stages.

HIERARCHY-OF-EFFECTS THEORY AND EMAIL MARKETING

Email marketing aims to generate conative, cognitive, and emotional responses from the targeted audiences through persuasion, education, and perception. The hierarchy-of-effects theory provides marketers with a practical framework that integrates various marketing constructs and variables to evaluate the marketing system and enhance these objectives' achievement. The model identifies different stages of consumer-company interactions and provides causal associated with each step, enabling marketers to characterize consumers' behaviors (Lorente-Páramo et al., 2021). AIDA (Attention, Interest, Desire, Action) framework is a popular model of hierarchy-of-effects theory used to analyze the effectiveness of email marketing. The four components of the model represent the various stages that consumers undergo before making a purchasing decision.

Attention

Attention is a cognitive resource that focuses on the level of devotion an individual applies to an object or promotional materials. Lorente-Páramo et al. (2021) indicate that attention has become an essential requirement for successful marketing campaigns since digital advertisements have led to consumers' exposure to 1000 to 5000 commercial communications every day. The increasing number of digital platforms has led to a significant shift in advertising strategies, with most companies exploring online opportunities (Utkarsh & Gupta, 2019). Examples of these online marketing channels include mobile technologies, such as cell phone TV and text messaging (SMS), email, online banner ads, and blogs (Danaher & Rossiter, 2011). These marketing strategies have varying stimulation effects on internet users, influencing a marketing campaign's success (Mandelli, 2005). Lorente-Páramo et al. (2021) explain that people make conscious decisions about their preferred stimuli after registering and processing the perceptual information provided by the ad. Therefore, email marketers need to ensure that the target audience's content is creative and relatable to attract their selective attention and increase the probability of positive reactions.

Interest

Interest is the feeling that occurs when a consumer begins to pay special attention to an object. Lorente-Páramo et al. (2021) identify it as a psychological state involving affective and cognitive aspects, occurring when an individual's sensory recognition begins to function at judgment-forming and attitudinal levels. Attaining this stage requires consumers to access relevant information regarding the brand or products they are making an opinion about. Heiens and Narayanaswamy (2016) explain that, unlike traditional marketing, consumers who access their emails are more focused on the promotional message. Therefore, marketers should ensure that the promotional content sent to provide all relevant information and links to additional sources to ensure that their target consumers understand the benefits of the products or services marketed (Danaher & Rossiter, 2011). The connection between attention and interest is evident in email marketing. For instance, only the sender and subject can be viewed (Lorente-Páramo et al., 2021). These components should be appealing enough to attract the recipient's attention and encourage them to open the email. Once the email is opened, the recipient makes a conscious decision to open the provided link or watch the video, reflecting their interest. Therefore, the first state, attention, is the entry point for the second stage of interest.

Desire

This AIDA stage focuses on consumers' aspiration to possess a particular product or service. Lorente-Páramo et al. (2021) define desire as a conscious impulse towards an object that can offer gratification and entertainment. A consumer's decision to buy a product is based on the belief that it provides particular desired benefits (Hyun-Hwa & Kim, 2010). Therefore, desire occurs when consumers believe the marketing content's credibility and feel the need to purchase the object. Utkarsh and Gupta (2019) indicate that companies successfully achieve positive purchasing intentions through consistent emails that increase the probability of positive word of mouth and brand loyalty. Consistency facilitates strengthening of the company-consumer relations, building trust and mutual understanding (Key, 2017). Therefore, frequent updates are likely to increases consumers' perceived credibility of the promotional messages, leading to increased sales (Heiens & Narayanaswamy, 2016). However, marketers should ensure that the messages are not over-sent to cause consumer irritation and a negative attitude towards the promotional campaign, causing their opt-out decisions. Key (2017) recommends personalized marketing information based on demographics and consumption patterns to avoid generating negative emotions and boost positive responses. Therefore, adequate planning and proper execution of the message strategy and structuring are essential to prevent potential negative impressions and consequences.

Action

This final stage occurs when consumers purchase the desired object. While the consumers experience a sense of accomplishment after acquiring the product or service they believe will be beneficial, the marketers and companies achieve the primary goal of marketing communications to increase sales (Mandelli, 2005). Although marketing focuses on establishing and maintaining relationships with potential and existing clients, the ultimate goal is to boost an organization's sales (Danaher & Rossiter, 2011). Consumption decision occurs in stages allowing consumers time to test and try the marketing campaign's credibility and understand the product's benefits. Lorente-Páramo et al. (2021) explain that action reflects a successful cognitive procedure developed by the marketer and occurs at the behavioral level. According to Hyun-Hwa and Kim (2010), shopping decisions involve thorough browsing and gathering information based on needs and desires. Therefore, the final purchasing decision occurs after the consumer is satisfied with the knowledge acquired about a brand and trust is established. Lorente-Páramo et al. (2021) recommend measuring action using the conversion rate (CR) to understand the email marketing campaigns' effectiveness. LukiÄ et al. (2014) define CR as the ratio of users who take actions and the total users who visited the email communication. For instance, a company can compare the number of email users who placed an order following a promotional message versus those who read the message but did not take any action. The primary benefit of undergoing the AIDA model is that they increase the probability of consumer retention. Since the process is built on active interactions and increased awareness and involves cognitive and emotional processes, the consumer is more likely to repeat the purchase.

THE IMPACT OF EMAIL ADVERTISING ON CONSUMER ATTITUDES AND BEHAVIORS

Email marketing changes the nature of communication between marketers and consumers, allowing them to become full participants of the process. The increased interactivity provided by this interaction channel ensures the availability of information, increased efficiency, and speed, influencing consumers' purchasing decisions (DuFrene et al., 2005). Therefore, email marketing can influence consumers' attitudes towards a company, its products, and services. However, Haq (2009) notes that previous research shows that most consumers tend to ignore promotional material both in traditional and internet marketing. These contradicting perceptions create a knowledge gap in email marketing's actual influence on consumer behaviors and attitudes.

Consumers' perceived value of email marketing depends on their relationship with the company or marketers. DuFrene et al. (2005) explain that contemporary marketers solve low trust and interaction rates by implementing permission-based emails that allow consumers to opt-in to a company's target list and frequently receive promotional information. This strategy increases interactivity by helping consumers' organize relevant information (Gibson & Hanson, 2018). For example, the targeted emails contain links that guide consumers to a company's particular section of the website where products matching their interests are displayed. The additional information enables the consumer to avoid navigating an entire webpage and instead directs them to the specific interest section. Fogel and Shlivko (2009) illustrate the significance of permission-based marketing by indicating that spam emails negatively influenced consumer behavior due to their intrusiveness and irritation. Positive actions are depicted when a customer gives consent to receive marketing messages or uses his/her data (LukiÄ et al., 2014). The level of permission given depends on the consumer's trust and confidence in the company or marketing, creating a healthy and mutually beneficial relationship.

Consumers' attitudes and behaviors towards email marketing depend on the appeal and nature of content deployed to target audiences. Haq (2009) indicates that consumers notice email promotions from the content shared and the offer's attractiveness. Therefore, the process of planning and executing requires high creativity to facilitate the integration of various visual and linguistic advertising features such as formal language, photos, videos, and font size and color (Sigurdsson et al., 2016). Kumar et al. (2014) associate the enthusiasm towards email and mobile marketing to integrate interactive features. Stern (2010) indicates that interactive marketing has gained the popularity that competes with other traditional marketing strategies such as television advertisements. Inability to design marketing messages properly can lead to a decline in response rates and prompt potential customers to unsubscribe to email newsletters that previously guided their buying decisions. Fogel and Shlivko (2009) argue that interactive email content click rate and click-to-open rates increase the consumers' curiosity about the content shared. Besides, it increases consumers' active engagement and participation, thus, boosting experience and influencing attitudes (Starr, 2006). Although interactive emails' primary goal is to inform consumers about the company, products, and services, it also entertains the audience. Haq (2009) indicates that consumer attitudes and behaviors towards email ads result from evaluations of their informativeness and entertainment. Due to the increased tech know-how, new generations prefer interactive and visual content since it requires them to act to full access information (Pentina & Hasty, 2009). The information and fun activities can influence the targeted consumers' feelings towards the brand, leading to their retention and loyalty.

Past experiences and loyalty can influence the length of time a client is willing to stay in a permission-based marketing program. Experience and trust influence consumers' online and offline buying behaviors, determining their relationships with marketers and companies. Kumar et al. (2014) suggest that marketers should evaluate transactional actions when modeling the marketing campaign. The process should involve evaluating consumers' purchasing decisions during their 'opt-in' and 'opt-out' moments to aid consistent improvements (Sigurdsson et al., 2016). Merisavo and Raulas (2004) explain that consumers maintain relationships with brands to enhance information processing, maintain a comfortable psychological state, and cognitive consistency. Customers' experiences with these mental states are likely to show their influence through purchasing behaviors, i.e., higher purchasing volumes (Starr, 2006). Analyzing such customers' histories can help the firm identify opt-in and opt-out patterns, enabling necessary improvements. For instance, Kumar et al. (2014) indicate that some customers take time to test a marketing program before opting in and opt-out after a short time due to its failure to meet expectations. Marketers can use a case to analyse the link between opt-in and opt-out duration and identify potential factors affecting consumers' behavioral and attitudinal changes to develop necessary program changes and boost consumer experiences.

Marketing communication timing can influence consumers' purchasing decisions and behaviors. Waheed and Jianhua (2018) explain that most e-marking messages fail to achieve the desired outcomes due to wrong timing where customers receive messages of products and services when they do not need them. Successful email marketing should be meaningful where the content is aligned with the customers' current needs (O'Connor, 2008). Kumar et al. (2014) explain that customers opt into a marketing program to access appropriate information about promotions and products that add value to their lives. Consumers perceive these programs as potential methods of reducing information search costs (Stern, 2010). Therefore, the inability to match consumer interests and demands with marketing communications can lower their interest, causing opt-out decisions. Besides, Drèze and Bonfrer (2008) identify the customer relationship duration as a significant component of marketing communication timing. Companies acquire more benefits by maintaining long-term relationships with their clients. The five permission levels identified by Marinova et al. (2002) involve a long-term process characterized by increased trust and confidence in a company, its products, services, and marketers. In long-term relationships, consumers interact more with the permission-based emails to gather more information about their favorite brand, leading to higher response rates, interactions, and sales.

Consumer demographics and perceived credibility can influence their willingness to interact with online marketing content. Haq et al. (2009) indicate that a company's reputation, integrity, and trustworthiness directly affect consumers' perception of ad value and their attitudes towards marketing. Most email recipients are likely to open and read marketing emails from reputable firms than non-reputable ones. Therefore, organizations aiming to seize opportunities created by digital platforms should work on improving their reputation and brand image to enhance trust (Gibson & Hanson, 2018). Consumer demographics such as age, education level, and gender influence their attitudes towards marketing and online purchasing behaviors. Waheed and Jianhua (2018) illustrate the impact of consumer personality traits by indicating that those with exploratory buying behavior tendencies (EBBT) are more likely to interact with promotional materials due to curiosity. Understanding consumer demographics can help personalize email ads to ensure that individual customers receive emails relevant to their personalities and demands.

CHALLENGES ASSOCIATED WITH EMAIL MARKETING

Despite the high ROI, reduced costs, and increased efficiency, unsolicited emails pose a significant threat to email marketing effectiveness. Reichhart et al. (2013) associate the rise in email marketing to increased penetration of mobile devices, which allow consumers access to the internet at any time. Unlike commercial emails, unsolicited emails are not permission-based, fail to comply with applicable legal regulations, are untargeted, can be offensive, malicious, and misleading (Melville et al., 2006). When companies send large volumes of emails to potential consumers, they may negatively affect the brand or the marketing campaigns' motives (Pentina & Hasty, 2009). Spammers' motivation to increase productivity despite the low response rates encourages them to extend promotional content deployment efforts without consideration of the recipients' attitudes and schedules (Murphy & Gomes 2003). In response to this problem, business organizations have implemented measures such as permission-based email marketing, which requires recipients' consent before receiving the promotional contents (O'Connor, 2008). However, spam emails have continued to challenge email marketing progress as some spammers continue to develop ways of avoiding filtering technologies.

Additionally, some governments have implemented legal statutes to control email marketing and protect users' data. For example, the 2003 US CANSPAM Act requires advertisers to label marketing messages, allow users to opt-in and out of marketing campaigns, and avoid distributing misleading and deceptive information (Reichhart et al., 2013). Opt-in and opt-out of marketing campaigns grant email users the freedom to choose which messages to receive and the companies to interact with. However, while this development can be beneficial to both marketers and companies as it instills consumers' confidence in the email marketing sector, it also poses lawsuit threats since most salespersons lack knowledge on specific requirements. For instance, Clarke III et al. (2005) indicates that the US Act requires marketers to include accurate content about the brand or products, a valid physical address, opt-out instructions, and clear subject lines. With these guidelines, unintentional failure to comply with the requirements would lead to lawsuits and expensive compensation requirements or jail terms for the salespersons required. Hemsley (2018) recommends that sales managers implement strategies to educate all the sales personnel about the laws and significance of ensuring compliance. The training can require time and financial resources, affecting the company's financial status. In addition, marketers' mistakes such as forgetting to include a vital requirement such as a valid physical address or errors in the subject line can lead to adverse consequences. However, the severity of the punishments for failing to comply with the legal establishments should motivate firms to implement stricter measures of reducing annoying junk emails.

The use of audio-visual promotion messages can distract recipients, leading to lower response rates. Scheinbaum et al. (2017) note that while audio-visual content can be used to grab consumers' attention, it can also interfere with their response to the delivered information. The importance of choosing the right multimedia elements is illustrated in Yang and Young's (2009) argument, indicating that apparel customers evaluate size, color, and texture to determine purchasing risks. Since businesses in virtual environments do not allow touching and observing a product before buying, consumers are forced to use other factors to evaluate the level of perceived risks of online buying. Therefore, choosing the right multimedia and maintaining a balance to ensure proper message delivery is an essential email marketing component. Murphy and Gomes (2003) report that email marketing further faces the challenge of consumer resistance, where some ignore and block all corporate emails regardless of their opt-in and opt-out status. The resistance results from consumers' negative impressions of the marketing campaign or unmet expectations of the product or services. Although companies struggle with identifying valid reasons for these consumer behaviors, Scheinbaum et al. (2017) recommend proper integration of audio-visual materials to create positive impressions. Interactive media plays a significant role in boosting consumers' response rate since it raises curiosity and encourages active participation. Marketers should ensure the correct use of text, video, photos, audios, emojis, and other graphical elements to avoid distractions and potential adverse consequences.