Abstract-Technologies). Online training also creates a personalized learning experience and reduces costs. In addition, e-learning is ideal for global corporations with people in multiple time zones, there is no need to coordinate travel and delivery schedules. Electronic mail (e-mail) is an asynchronous medium, which allows participants to control their own timetables and fit learning around their other commitments. The present study aimed to examine the effect of e-mailing on vocabulary retention of Iranian EFL learners. Forty participants were assigned into experimental and control groups. The participants received English words as well as definitions and example sentences either on paper or through e-mail messages in a spaced and scheduled pattern of delivery three times a week throughout 10 sessions. Students' statues in retention of vocabulary were compared at the end of the study. The obtained results showed that the use of e-mail technology can enhance the retention of vocabulary. This study also provides pedagogical implications for utilizing e-mail as an effective and flexible learning tool.