This paper presents results from an experimental evaluation of an intervention designed to enhance virtual student support. During the 2019-2020 school year, randomly selected mentors in a school-based mentoring program received monthly reminders with tips for communicating with youth via text, email, and phone. Unexpectedly, the results showed that although the nudges did not impact the frequency of mentor outreach (student-reported), they reduced the rate at which students reached out (mentor-reported) and saw themselves as responsive to their mentors. Moreover, and possibly as a consequence, mentors who received the intervention felt less connected to students and less satisfied with their mentoring relationships, and treated students gained less than comparison students from the mentoring program as a whole in terms of their personal and attitudinal growth. The findings add important nuance to the evidence on how behavioral interventions in educational contexts operate. Although past studies find that nudges can support engagement in discrete tasks, these findings suggest that prescribing relational practices may be less effective. Thus, mentor supports must be carefully designed in order to yield the intended benefits for students.