The purpose of this study was to: (a) investigate the effects of email to enhance learners' use of self-regulation strategies; (b) examine different effects between email list and individually addressed notes on the enhancement of self-regulation; (c) observe and record changes in self-regulation and self-efficacy; and (d) explore the relationships among self-regulation, self-efficacy, and achievement. For an entire semester, 103 college students enrolled in an online, asynchronous mathematics course participated in this study. They were randomly assigned to one of three groups. The first group received self-regulation strategies without personalized messages; the second group received self-regulation strategies with personalized messages; and the third group received neither self-regulation strategies nor personalized messages. Results indicated that there was no statistically significant effect for the email treatments but a statistically significant relationship was observed between self-efficacy and achievement. The findings are discussed with an emphasis on the reciprocal relations between self-efficacy and self-regulation.