Background: As personalization has become a common CRM strategy for companies to create valuable relationships with customers, users are receiving an increased amount of personalized communication, further research is needed on the influence of content personalization in specific channels, to improve customer engagement. 

Purpose: This paper seeks to analyse the influence of eCRM content personalization strategies on the consumer engagement performance of email marketing campaigns building upon existing knowledge about the benefits and opportunities of personalization strategies. 

Method: The selected method is quantitative, using A/B testing, based on the comparison of different variations on two identical segments where the only differentiated element is the one being evaluated. Two controlled experiments evaluating subject line and image personalization are performed evaluating four metric of email marketing performance: open rate, click-through rate, conversion rate and unsubscribe rate. 

Conclusion: The results of the two controlled experiments performed for this research, subject line personalization and image personalization, complement past literature on content personalization strategies (Bertrand et al., 2010; Carlota Rocha et al., 2023; Munz et al., 2020; Sahni et al., 2018) by demonstrating the statistically significant positive influence of content personalization on email marketing performance and reinforcing the importance of familiarity with the brand or product on reducing the probability of bad outcomes.