The effect of digital marketing transformation trends on consumers’ purchase intention in B2B businesses: The moderating role of brand awareness

Abstract Digital marketing transformation is one of the important elements in a business’s long-term plan. Furthermore, choosing the most optimizing and suitable marketing strategy is not really simple with B2B enterprise. Based on the theory of planned behavior and the theory of consumer behavior, this study aims to explain the effects digital marketing forms on customer attitudes toward digital marketing and purchase intention. Research sample with a size of 210 potential customers, from the important people in the B2B purchasing chain at the enterprise. After being tested through partial least squares structural equation modelling techniques, resulted in 3 out of 4 digital marketing forms were rated as important and appropriate. Furthermore, the study also explored that brand awareness only moderates the relationship between attitude toward digital marketing and customer purchase intention. The results would help managers have the right direction for the business strategy to adapt and develop the business despite any difficult circumstances.


Introduction
These days, digital marketing has become part of people's daily lives around the world. As of January 2021, there were 4.66 billion internet users worldwide-59.5% of the global population (Statista, 2021). Vietnam alone has 70.3% of the population using the Internet, an increase of 0.8% over the same period last year. In addition, people are spending more and more time on the

PUBLIC INTEREST STATEMENT
Digital Marketing is increasingly showing its important role in the business strategy of businesses, especially B2B enterprises. This study provides corroboration that it is digital marketing practices that have a significant impact on customer attitudes towards digital marketing and customer purchase intention. Customers' attitudes towards digital marketing are the mediators between digital marketing strategies and purchase intentions. Moreover, in addition to digital marketing strategies, brand awareness also plays an important role in this relationship.About Authors Dr. Nguyen Ngoc Hien is a lecture at Faculty of Business Administration, Industrial University of Ho Chi Minh City, Vietnam. His research interests include Marrketing, organization behaviour, corporate social responsibility and organizational psychology. Tran Nguyen Huynh Nhu is a student in the Master of Business Administration at the Industrial University of Ho Chi Minh City. She has been engaged in academic research since 2019 mainly on the topic of Marketing and CSR internet, not only to search for information about products and services but also to communicate with other customers about their experiences and interactions with businesses. Digital marketing has been proven to change shopper behavior (Khwaja et al., 2020). Many businesses have responded that social media and digital marketing have become integral components of their business marketing plan (Cait Lamberton & Stephen, 2016). The use of digital marketing allows companies to achieve their marketing goals at a relatively low cost (Ajina & Tvaronavičienė, 2019). Organizations can significantly benefit from the creation of social media, an integral element of the overall business strategy (Salma et al., 2016).
For B2B enterprises, lasting relationships only develop gradually over time (Quinton & Wilson, 2016). Different from B2C business, because no previous research has determined which digital marketing medium is important in B2B relationships, use to contribute to optimizing customer's purchase intention (Guesalaga, 2016).
In addition, the Covid-19 epidemic has negatively impacted the development of the global economy in both micro and macro perspective (Patma et al., 2021). This crisis requires companies over the world both in Vietnam, to develop and implement appropriate strategies to adapt to the pandemic context. Previous studies on crisis management focused more on topics such as organizational capacity (Andreou et al., 2017;Parker & Ameen, 2018), corporate response (Hale et al., 2005;Runyan, 2006) human resource management (Harvey & Haines Iii, 2005;Lee & Warner, 2005), and corporate social responsibility (Bundy & Pfarrer, 2015). Especialized, in the context of the Covid-19 pandemic, research by Patma et al. (2021) explained the behavior of small and medium enterprises in applying internet/e-business technology, which will affect digital marketing and SME sustainability. The above-mentioned studies are certainly of great significance to businesses in responding to pandemics and crises. However, at present, the subject of marketing, above all digital marketing, is an important form of innovation for which there has not been a comprehensive study on their value, which leaves B2B professionals uncertain about their effectiveness (Krings et al., 2021). see Table 1.
During the Covid-19 pandemic, not only the needs and buying behavior of customers have been changing partly, but also internet and social media have contributed to changing it (Yogesh, 2021). It was consumers who were spending more time buying online that digital marketing thrives during the pandemic (Coresight Research, 2020). Furthermore, digital platforms are strongly believed to be a sustainable growth strategy (Verhoef et al., 2021). The motives emphasize the significance of the digital marketing transformation for the survival of the business. While everyone must isolate at home and limit direct contact to minimize the possibility of infection; enterprises must grasp the situation and pay attention to develop their online marketing channels quickly (Al-Hattami & Gomez Corona, 2021) Measuring the effectiveness of each strategy in attracting purchases has huge implications for digital marketing at this time and in the future of B2B businesses. In the context of the covid 19 pandemic, the significant question is: Which digital marketing methods affect B2B customer purchase intention? and the aim of the study was shaped based on the lack of research on this issue. First of all, the study finds out the impact of digital marketing on customers' attitudes towards digital marketing and purchase intentions at B2B businesses in the context of the complicated Covid situation in Vietnam. Secondly, study the moderating role of Brand awareness and the mediating role of customer attitude factors toward digital marketing in this study.
To accomplish this research objective, consumer behavior theory (Kotler et al., 2007) is suitable to explain the relationships between digital marketing, customer attitudes towards marketing, and purchase intention. The fact that marketers understand what factors have influenced customers, then optimize to lead to purchase intention, and behavioral intention is also a key factor when evaluating the actual behavior of customers (Fishbein & Ajzen, 1977).
The rest of the study is structured as follows: Part 2 introduces the literature on current forms of digital marketing and B2B customers' purchase intentions in the context of the Covid-19 pandemic. The third part is the presentation of the model and the hypothesis. Research methods and scales will be presented in detail in section 4 of the paper. Research results will be presented in section 5. And an in-depth discussion in the 6 sections. Finally, the conclusion with a brief assessment of the limitations of the study as well as suggestions for future research.

Digital marketing
Over the past two decades, brands and businesses have changed because of digitalization. This strategy is becoming more and more popular and especially when it is gradually becoming a global trend. The American Marketing Association provides an overarching definition of digital marketing, encompassing most of the activities, organizations, and processes stimulated by digital technologies to communicate, create and bring value to customers (American Marketing Association, 2013). However, according to Royle and Laing (2014) digital marketing is a sub-branch of traditional marketing and uses modern channels to place products and mainly to communicate with stakeholders. Media such as web, e-mail, wireless media combined with digital data are the tools that manage all activities in digital marketing (Chaffey & Ellis-Chadwick, 2019). On the other hand, Todor (2016) found that digital marketing is not traditional marketing driven by digital factors, but rather a new approach with its own characteristics and dynamics, which are well understood so that effective marketing tactics and strategies can be selected. Likewise, Dara (2016) argues that digital marketing effectively increases the reach of customers' perceptions and purchasing behavior. From the above definitions, it is easy to see that the common point of digital marketing includes 3 main factors: Using digital media, approaching customers in a digital and interactive with them.

Forms of digital marketing
Although mention to Digital marketing, can not think of effective online advertising channels such as Facebook Ads, Google Ads or email marketing, affiliate marketing, forgetting that the essence of digital marketing is marketing on a digital platform.

Customer attitudes towards digital marketing
According to Kotler (2000), an individual's attitude is their evaluations, feelings of emotional attachment, and propensity to act toward some object or idea, it will be changed over time as individuals approach new concepts about those ideas or objects (Shaouf et al., 2016). Specifically, Attitudes towards digital marketing as customer behavior towards digital marketing, it can be indicated through a consumer's positive or negative response to particular digital marketing . Besides, Mehta (2000) said that consumers' attitude towards advertising is one of the indicators that affect advertising effectiveness because purchase intention will increase when the attitude towards advertising is more positive (Hameed et al., 2020). In this study, attitude toward digital marketing is considered an important variable in assessing the success of digital marketing forms (Eid et al., 2020). The key aspect here is the perception of the advertising medium, which strongly reflects consumer attitudes towards forms of digital marketing. they want, similar to decision making (Mirabi et al., 2015). In this study, purchase intention is understood as the combination of consumers' interest in a product and the ability to buy that product (A. J. Kim & Ko, 2010). Many previous studies support the view that attitudes and preferences towards a brand or product will be directly related to the purchase intention of the customer (Mai et al., 2021;Peña-García et al., 2020). Nevertheless, the purchase intention in the B2B model is different from the B2C model. Furthermore, compared with B2C, the B2B purchase intention process is typically longer, more technical, and more complex (Lilien, 2016). Therefore, B2B business marketing strategies are also more different.

Theory of consumer behavior and theory of planned behavior
This study attempts to find out the relationship between forms of digital marketing, customer attitudes towards marketing, and purchase intention. Accordingly, the theory of consumer behavior by Kotler (Kotler et al., 2007) demonstrates that marketing activities affect purchase intention and generate customers' certain reactions, specifically in this study such as search engine advertising, social media, content marketing, and email marketing. These strategies will affect customers and bring about many different reactions. Combined with individual attitudes, one of the three main elements of the theory of planned behavior (Ajzen, 1991), both positive and negative attitudes influence the performance of that behavior, the attitude towards the marketing that businesses apply to approach B2B customers was mentioned. Moreover, the theory of planned behavior provides a brief explanation of the informative and motivational influences on behavior and can be considered a model of intentional processing (Ajzen, 1991).

Research hypotheses
There are many forms of digital marketing in the market, this study presented the 4 most commonly used and trending methods. Four methods were identified from various sources: search engine advertising (Chaffey & Ellis-Chadwick, 2019), Content Marketing, Social Media, Email Marketing (Forbes, 2014). Besides, the mediating role of customers' attitudes towards marketing in the relationship between these digital marketing forms and purchase intention was emphasized; Brand awareness plays moderating role between the relationship of digital marketing, customer attitudes towards marketing, and purchase intention.

Search engine advertising
It is strongly believed that search engines play an important role in the Internet marketing strategy of many B2B companies (Kamis & Stohr, 2006) and can help enterprises bring many distinct advantages for both short and long-term plans (Bayer et al., 2020). Moreover, it is an intermediaries tool between companies and consumers (De Corniere & de Nijs, 2016); When customers are forced to search and update information online and limit direct communication, so it gradually becomes a major marketing channel in online advertising today (Fuxman et al., 2008). Primarily, the higher the advertising positions in search results, the more effects on customers (Athey & Ellison, 2011), products will have more visibility, easily get more attention from customers, and influence the purchase intention (Chalil et al., 2020). To assess the search engine advertising strategy as an important method that should be applied in B2B enterprises in the context of the pandemic, when all information is transmitted over the internet, the hypothesis is given as follows: H 1a : Search engine advertising has a positive effect on customer attitudes towards digital marketing of B2B businesses H 1b : Search engine advertising has a positive effect on customers purchase intention of B2B businesses

Content marketing
The art of communicating with customers or potential customers without selling activities is through content marketing (Ilmi et al., 2018). Trust and strong relationships with customers in B2B businesses is easily built, just need to provide useful content and the advantage foundation for long-term competitiveness (Kiráľová & Pavlíčeka, 2015). This even attract potential customers, no need to use the product, the content affects customers' attitudes and buying goals (Silbert Jose, 2021). Content marketing will contain valuable product/service reviews as well as relevant information and have a positive influence on customers' purchasing intention (Sudarsono et al., 2020). It is expected that, during the period of social distancing, when customers have more time to learn about products, if customers' evaluations of marketing content are positive, customers' attitudes and purchase intentions are also positive. Therefore, the hypothesis about the impact of content marketing is proposed as follows: H 2a : Content marketing has a positive effect on customer attitudes towards digital marketing of B2B businesses H 2b : Content marketing has a positive effect on customers purchase intention of B2B businesses

Social media
The process of marketing content and information to gain massive traffic or brand attention, collectively known as social media (Krishnamurthy & Sin, 2014). This strategy allows businesses to connect with customers, raise brand awareness, influence consumer attitudes, get feedback on products and services, thereby helping to increase gross revenue (Algharabat et al., 2018). Consumers increasingly rely on the media they come into contact with day by day (Herhausen et al., 2020). Although B2B businesses have a great interest in social media, the majority of B2B companies have not taken its use seriously (Michaelidou et al., 2011). However, Davis (2010) found that B2B enterprises could take advantage of social media networks by communicating and attachment brand, building customer trust. The influential features as sharing and interacting online in a timely manner between businesses and customers are also one of the advantages that need to be promoted (Cartwright et al., 2021), especially when people are limited in face-to-face communication in the context of the epidemic. Therefore, social networks are expected to support B2B businesses in the process of reaching customers, helping to influence attitudes towards marketing and purchase intentions. The following hypothesis is proposed: H 3a : Social media has a positive effect on customer attitudes towards digital marketing of B2B businesses H 3b : Social media has a positive effect on customers purchase intention of B2B businesses

Email marketing
It is demonstrated that email marketing is one of the most popular marketing tools for many businesses (Dash et al., 2021) even before and during the Covid epidemic and its impact. Because of some outstanding reasons such as saving costs, familiar and is especially important for companies looking to build and maintain relationships with customers (McCloskey, 2006). It is also a system of customer data and messages sent to people who may be interested in purchasing products (Ellis-Chadwick & Doherty, 2012). Even though email is essentially a two-way communication channel, for B2B businesses it is often used as a one-way channel to send newsletters or advertisements. Furthermore, email is seen as a channel that provides marketers with the opportunity to engage with their consumers by easily customizing the content or offers in the email to best suit their needs with each object, this helps not only having a better impression of the business but also building loyalty and stronger brand recognition in consumers (Samantaray & Pradhan, 2020). So, the impact of email marketing on customers' attitudes towards digital marketing and purchase intention is given as follows: H 4a : Email marketing has a positive effect on customer attitudes towards digital marketing of B2B businesses H 4b : Email marketing has a positive effect on customers purchase intention of B2B businesses

Attitude toward digital marketing
Customers' attitudes play a meaningful role in the effectiveness of any advertising campaign (Lou & Yuan, 2019), which is reflected in their thoughts and feelings and subsequently affects their attitudes toward digital advertising (MacKenzie & Lutz, 1989b). Good advertising could change a person's perception, and advertising with beautiful images can have a significant impact on catching customers' connection with a product (Giao et al., 2020). Furthermore, customer attitude toward digital marketing has a direct influence on purchase intention (Weinberger et al., 2017). When consumers receive digital marketing messages related to products or services, they behave quickly and tend to buy more (Hameed et al., 2020); Nevertheless, it depends on the perceived value of the product or service of each person (Monroe, 2011), which is currently economically and psychologically affected by the complexity of the epidemic. So, the hypothesis of the relationship between customer attitudes towards digital marketing, digital marketing methods, and purchase intention is proposed as follows: H 5 : Attitude toward digital marketing of B2B businesses has a positive effect on purchase intention.

Brand awareness
A customer's ability to recognize and recall a brand in different situations and influence a customer's purchase decision is understood as brand awareness (Kapferer, 2008). In particular, for B2B enterprises, a strong brand provides several benefits including brand extensions, distribution capabilities, and stronger buyer-supplier relationships (Leek & Christodoulides, 2011) In the context of social media, when customers have positive interactions with the brand on social media, their satisfaction is improved leads to the desire to buy the brand (Martín-Consuegra et al., 2019;Tran Le Na et al., 2021). With the period of limited direct movement, the trustworthiness when choosing a partner is also strongly influenced by the brand reputation. Therefore, for branded products, customers will have more trust in digital marketing information and have a positive impact on purchase intention (Verlegh et al., 2005). Even brand awareness influences future brand product choices (Dabbous & Barakat, 2020). Finally, the role of brand awareness is expected as follows: H 7 (a-d): When brand awareness is more positive: a. The positive relationship between search engine advertising and attitude toward digital marketing will be strengthened.
b. The positive relationship between content marketing and attitude toward digital marketing will be strengthened.
c. The positive relationship between social media and attitude toward digital marketing will be strengthened.
d. The positive relationship between email marketing and attitude toward digital marketing will be strengthened.
e. The positive relationship between customer attitudes towards digital marketing and customers purchase intention will be strengthened.
Summary of research hypotheses shown in Figure 1.

Measures
This study used scales based on the previous ones, which have been put through in different contexts. In order to better fit the context of this study, there have been adjustments to the original scale as shown in Table 2. To confirm the proposed theoretical model, a questionnaire that included 2 main parts was brought into existence. Part 1, the questions about participants' demographics, including gender, age, education, occupation, awareness of digital marketing strategy. In Part 2, respondents were asked to evaluate multiple parameters of the impact of digital marketing in the mechanical enterprises. (on a Likert scale of 5 points from two extremes being "strongly disagree" and "strongly agree"). This part has 25 questions that evaluate the four below forms of digital marketing, namely 3 questions about search engine advertising, content marketing has been appraised by 3 questions, 5 questions about social networks, 3 questions about email marketing, and three other aspects of brand awareness (4 sentences), customer's attitude toward digital marketing (3 questions), purchase intention (4 questions). After designing, the survey draft was reviewed by experts, who are 5 lecturers teaching E-commerce. Next, a pilot study was conducted with 30 people who are key people in B2B purchases to assess the level of clarity and interest in the observed variables. Several modifications have been made to the questions to remove ambiguity and confusion and thus improve it.

Data colection
Considering the impact of the Covid-19 the survey was collected online. The data collection is carried out in the last 4 months of 2021. The survey respondents are mainly business people who have been intending to buy from B2B enterprises in the mechanical industry in Vietnam. We target the survey subjects who are responsible for purchasing decisions at B2B businesses, not only business owners but also managers and personnel in related departments. The majority of those participants are on average 40-45 years old and provide us with a lot of substantial information about the impact of digital marketing. The results of the questionnaire will be investigated in many aspects of digital marketing strategy implementation, because of the variety of career levels. After removing a few incomplete answers out of a total of 227 forms received from respondents, we resolved to 210 responses that met all the criteria for a completed questionnaire full of information. The normality of the data was confirmed.
For data analysis, partial least squares structural equations modeling (PLS-SEM) were considered the best choice for this case, because of the core of our research model and hypothesized relationships were explanations and prediction, and given the expected managerial implications of the study , with the SPSS 24.0 software and Smartpls 3.3 for assessing the measurements and estimate the model parameters. Measurement model evaluation and structural model evaluation are two steps in performing the analysis (J. Hair et al., 2010).

Descriptive statistics for sample
A total of 210 valid observations were accessed and the demographic details are shown in Table 1. Male-dominant respondents reach 75.7%, which is almost twice as high as the number of female respondents (24.3%). Most of them have an important role in the company such as Director/ Business Owner with 42.9% and CEO/Manager with 29.5%, 10% from Self-employed position and

Measurement model
Harman's single factor is used here because the correlation relationship between the dependent and independent variables is affected by the problem of the common method bias (Podsakoff et al., 2003). One fixed factor goes along with the other six. The total variance extracted for these 7 factors is 69.92%. The common method bias is not a serious problem (Podsakoff et al., 2003) since the first factor accounts for only 27.6% of the total variance extracted for the entire model (<50%).
Cronbach's alpha, composite reliability (J. Hair et al., 2010), and RhoA coefficient (Dijkstra & Henseler, 2015) are the coefficients used to evaluate internal consistency reliability. Convergent validity was assessed through Outer loading of observed variables and average variance extracted (AVE). The scale is accepted when the AVE value is greater than 0.5 and the outer loading value is greater than 0.7 (J. Hair et al., 2010). Evaluation of the significance of the data by performing Bootstrap 5,000 times (J. Hair et al., 2010).
From Table 2, it can be seen that the Cronbach's Alpha coefficient of the concepts is in the range [0.7-0.8], the composite reliability is in the range [0.8-0.9] and the RhoA coefficient is > 0.5, which shows that the scales are achieved reliability (J. Hair et al., 2010) The SM5 variable has an outer loading = 0.373 less than 0.7, so it was removed from the model after performing the convergence value test. Therefore, the study has met the criteria of convergence value after removing the SM5 variable from the model, and the AVE and outer loading values of the observed boundaries are satisfactory. (Table 2) Cross loadings coefficient, Fornell-Larker criteria, and Heterotrait-Monotrait Ratio of Correlations (HTMT) are three indexes used to evaluate the discriminant validity of the scale (J. F. Hair et al., 2017). After testing, the cross-loadings coefficient in its structure is much larger than in the other structure. The square root of the AVE of each structure in the Fornell-Larcker criterion results table (Table 3) is larger than the correlation coefficient between the structures. In addition, the discriminant validity is ensured thanks to the HTMT value (Table 4) less than 0.9 . Furthermore, the scale reached the discriminant value after running Bootstrap 5,000 times showing that the confidence interval results from the HTMT value were from 2.5% to 97.5% excluding the value 1.

Direct impact
To evaluate the phenomenon of multicollinearity between independent variables, the variance inflation factor (VIF) will be used. The research model is divided into 3 models with 1 dependent variable because there are many dependent variables. The scale has no multicollinearity phenomenon due to the result of the coefficient VIF < 2.
Coefficient of Determination (R 2 ) was used to measure the predictive strength of the independent variables. The predictive level of the variable Attitude toward digital marketing is considered moderate (R 2 Attitude toward digital marketing = 0.338) and the predictive level of the variable Purchase Intention is considered moderate (R 2 Purchase Intention = 0.546) according to the results shown above Table 5 and Figure 2.
Besides, the out-of-sample predictive power is evaluated through predictive relevance (Q 2 ). The results of Table 5 also show that the predictive power of the model (J. Hair et al., 2010) is also supported because the Q 2 coefficients of the dependent variables are all larger than 0. As suggested by J. F. Hair et al. (2017), the statistical significance of the regression coefficients was tested through the Bootstrap procedure 5,000 times. From Table 5 and Figure 2, it is shown that with more than 95% confidence, the relationships in the theoretical model include: H 1a , H 2a , H 2b , H 3a , H 5 have statistical significance. The remaining relationships are not statistically significant at the 95% confidence level.

Mediating effects
Testing the mediating role of Attitude toward digital marketing in the relationship between the factors of Content marketing, Social Media, Email Marketing, Search Engine Advertising, and Purchase Intention is considered as the important objective of this study. The mediating effects can be measured by two factors: the relationship between Digital Marketing factors such as Content Marketing, Social Media, Email Marketing, and Search Engine Advertising Attitude towards Marketing and the relationship between the factors Attitude towards Marketing and Purchase Intention (Cheung & Lau, 2008).  Table 6 demonstrates the results as Attitude towards Marketing is the mediating variable between the relationship between Content Marketing, Social Marketing and Search Engine Advertising and Purchase Intention.

Moderating effects
After evaluating the measurement model with the presence of a moderator variable, the concept of measuring Brand Awareness is reliable (Cronbach's alpha = 0.816, Composite Reliability = 0.879, and value (AVE = 0.646, square root of AVE of Brand Awareness is greater than the correlation coefficient between constructs, HTMT < 0.9 and the confidence interval of Brand Awareness HTMT value does not contain 1) Next, use the 2-stage approach of Chin et al. (2003) to evaluate the impact of the Brand Awareness. In the first stage, estimate the main impact model. Stage 2, multiply the moderator variables and exogenous variables to measure the interaction term. Table 7 illustrates that Brand Awareness plays a role in moderating the relationship between Attitude towards Marketing and Purchase Intention. Thus, as Brand Awareness increases, the influence of Attitude towards Marketing on Purchase Intention also increases. Therefore, hypothesis H7e is supported.

Discussion
This study was conducted to evaluate the impact of digital marketing strategies on attitudes toward marketing and the purchase intentions of customers. Understanding customer attitudes towards a particular digital marketing strategy and developing it can close the customer perception gap in B2B businesses (Dash et al., 2021) This study attempted to evaluate the results based on a cross-sectional sample of 210 people with an interest in buying from a B2B business.
Offering some new insights into the adoption of digital marketing in B2B businesses during the pandemic is also one of the important functions of this study. In addition, during the pandemic, when people are active in a virtual environment, the study also outlines the impact of the pandemic on B2B businesses and how to apply sensitive digital marketing strategies to adapt to the environment.
Four digital marketing strategies have been studied here with eight hypotheses about the relationship between them and attitudes towards marketing and purchase intention. Three of them, Search Engine Advertising, Social media, content marketing are considered to have a positive impact on the customer attitude toward digital marketing in B2B businesses, respectively the hypotheses H 1a , H 2a , H 3a . The results of this study support these three hypotheses, reinforcing the findings of previous studies on the effects Search Engine Advertising (Punjani & Kumar, 2021), Social media (Alalwan, 2018;Kundu, 2021) and content marketing (Molina et al., 2020;Olson et al., 2021;Sahni et al., 2018) in influencing attitudes  Dash et al. (2021) study in the B2B context. A satisfactory explanation for this research result may be that the survey respondents did not want to delve into the product features and did not properly decode the information sent by the advertiser.
As for the effect on purchase intention, only the H 3B hypothesis is supported that content marketing has a positive and significant effect on this factor, which is consistent with the results reported in previous literature on content marketing (Kong et al., 2021;Olson et al., 2021) reinforces the idea that content strategy is an important key to determining marketing effectiveness (Molina et al., 2020). All three relationships between Search Engine Advertising, Social media, and email marketing on purchase intention were not supported in this study (Chalil et al., 2020;Kundu, 2021).
Research results also provide support for hypothesis H 5 about the impact of customer attitude toward Digital Marketing and purchase intention. Repeatedly, this finding is completely consistent with previous studies by Oscar and Louis (2021) and Wahid and Ahmed (2011). Furthermore, the factor of customer attitude toward digital marketing plays a mediating role in this study. It is the mediator between search engine advertising, social media, content marketing, and customer purchase intention (H6a-c). When customers have a more positive attitude towards digital strategies, more likely they are to buy. The other factor is that email marketing has no impact on both customers' attitudes towards digital marketing and purchase intention (H6d), which reinforces some of the earlier studies of Olson et al. (2021) and Rehman et al. (2014) Last but not least, the study also discovered the moderating role of brand awareness. However, like Kim's previous study (Kim, 2018) brand awareness only plays a moderating role in the relationship between customers' attitudes towards digital marketing and purchase intention (H7e), and with 4 marketing strategies, the role is not significant (H7a-d).

Conclusion
The related issues of advertising are increasing rapidly, becoming the focus of attention of both researchers and practitioners in the marketing sector. Therefore, this study was conducted to expand the current understanding of the main aspects related to digital marketing and their impact on customer purchase intention.

Theoretical contributions
It was not by accident that digital marketing becomes more and more important these days, especially when businesses are getting used to interacting with users on a global scale and solving important digital marketing problems (Dash et al., 2021). The various effects of current popular digital marketing strategies have been specifically pointed out by the study. However, in the B2B business environment, there is still little research on these relationships as well as the impact of digital marketing strategies on customer attitudes and purchase intentions. Therefore, by capturing some of the key elements of the current research model, it provides some specific significant theoretical contributions as follows: Foremost, the study contributes to the previous research literature in expanding understanding of the role digital marketing plays in B2B businesses. Over the years, researchers have become increasingly interested in the direct impact of digital marketing on B2B businesses, so the study's findings add to an increasingly popular field of research.
Secondly, the study has extended the theory of consumer behavior by (a) Confirming the relationship between customer attitudes towards digital marketing has a significant impact on the purchase intention of customers (b) testing the role of brand awareness in this relationship in the Vietnamese market. This is quite important in terms of the branding building process as well as identifying the right digital marketing strategies in mechanical enterprises' business plans.
This study also generalizes the impact of digital marketing methods on B2B businesses during the pandemic. As such, it provides some background for future research on the deep impact of digital marketing approaches in a variety of contexts. With the continuous development of technology, geographical, demographic or other industry contexts will potentially become new avenues of research.

Practical contributions
No one could have predicted or foreseen the state of the Covid-19 pandemic development. However, in order to survive and adapt in a difficult context, people must change to be more suitable and come up with a treatment plan to face them. The results of the study have provided an understanding of effective and appropriate digital marketing strategies for B2B businesses when major communication activity is done through the virtual world and public devices technology, this can help businesses have a foundation and come up with a way to reach their customers more effectively.
Regarding digital marketing strategy, enterprises can consider three strategies, namely search engine advertising, social media, and content marketing to increase the positivity of customers' attitudes towards customers. Thereby affecting the purchase intention of customers. Moreover, content marketing is an extremely important factor because it affects both the customer's attitude toward digital marketing and also purchases intention. Combining interesting, useful content with other methods can help create breakthrough effects. By determining the digital marketing strategies that work with their business model, mechanical businesses can save a lot of unnecessary costs if they comprehensive investment without selectivity in all campaigns existing digital marketing strategies in the market especially in the difficult situation in all aspects due to the pandemic impact.
In addition, increasing brand awareness is something to consider and focus on in long-term marketing plans. Because research shows that brand awareness has a direct impact on the relationship between attitude toward digital marketing and purchase intention. And B2B purchases have to go through many stages of thorough research, having a powerful brand that can trust and positively impact customers and it will be a huge outstanding compared to other competitors in the same industry.

Limitations and directions for future research
Although this study has successfully shown the impact of digital marketing factors on customers' attitudes and purchase intention, there are still some limitations in this study and may be considered to be addressed in the future. One of the limitations of this study is the geographical approach, we surveyed the scale of mechanical businesses in Ho Chi Minh City. Therefore, the data are generalized only.
Another limitation is the number of digital marketing strategies that were devised through expert interviews and data relatively little. Furthermore, It can't be denied that many digital marketing platforms are emerging and challenging the sustained effectiveness of current methods shown in the study. Therefore, it is not possible to make general statements about the effectiveness of these digital marketing strategies as well as universally applicable to most industries. Nevertheless, this is also a potential development direction for expansion in future research. In addition, culture and generation are also considered as challenging criteria to create combinations of methods currently under consideration. You are free to: Share -copy and redistribute the material in any medium or format. Adapt -remix, transform, and build upon the material for any purpose, even commercially. The licensor cannot revoke these freedoms as long as you follow the license terms.
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Research construct Items Source
Purchase intention PI1. I would be happy to purchase this advertised product in the future. So et al., 2018;Talwar et al., 2020 PI2. I plan to use the advertised product in the future.
PI3. I want to take more time to learn about this product because I want to use it in the future PI4. I plan to buy this product in my next time