This study explored long-term effect of explicit instruction on English as a foreign language (EFL) learners’ pragmatic competence when writing emails in English to examine Korean university students’ usage of forms of address when writing emails to faculty. The data comprised of 94 English emails written by 32 Korean university students in Korea. Over two weeks, Korean EFL students received four hours of instructions on how to write an appropriate email to faculty members. Data were collected quantitively and qualitatively through email writing assignments in pretest, immediate posttest, and delayed posttest. A follow-up interview was administered. A descriptive analysis of usage frequency of address forms was conducted to examine changes between before and after instruction. Results indicated that Korean EFL students obtained pragmatic competence focusing on forms of address. Regarding retention effect, findings showed that pragmatic competence was retained over an extended period (i.e., 10 months). In addition, through interview, it was found that participants showed enhanced awareness of forms of address along with norms of target culture through the instruction. Further implications of this study are given in terms of instruction on email pragmatics in the EFL environment, particularly in academia.