Electronic mental health services (eMHSs) offer additional options for the dissemination of psychological interventions for university students. Still, many university students are reluctant to use eMHSs. Narrative messages may help increase the awareness and acceptance of quality-approved programs. However, little is known about the usefulness of narrative messages to improve attitudes towards eMHSs. In this experiment, we thus aimed to explore in how far different ways of targeting information to students affect their attitudes towards eMHSs for stress prevention and therapy, and to identify potential determinants of attitude change. N = 451 students (Mean = 32.6 years, SD = 10.2, 75% female, 7% with eMHS experience) were randomly assigned to one of four study arms involving information designed to induce different levels of perceived similarity. While the active control condition only received general information (arm 1, “information only”, n = 116), the other experimental arms were additionally exposed to testimonials on specific eMHSs either addressing an unspecified audience (arm 2, n = 112), employees (arm 3, n = 115) or working university students (arm 4, n = 108). Two-way ANOVA revealed no impact of information on the alteration of attitudes towards eMHSs for stress coping (d = 0.20). Only a small effect of target-group specific testimonials on attitudes towards online therapies was identified at post-intervention (d = 0.29). Regression analyses demonstrated significant influences of source credibility and perceived similarity on attitudes for preventative eMHSs (p_s<0.01), as well as a partial mediation effect of perceived similarity in favor of testimonials targeted to students (95% CI [0.22, 0.50]). Overall, this study indicated no meaningful impact of information on attitudes and limited evidence for benefits of tailored narrative messages. Since attitudes were already positive at baseline, further research with a representative student sample mimicking real-world decision scenarios is needed to gain an in-depth understanding of acceptance-facilitating message features that may contribute to promote the adoption of evidence-based eMHSs.