The study analyzed a corpus of 40 emails of requests composed by Vietnamese students to their university lecturers. The study purpose was to identify politeness strategies composed by Vietnamese students using Brown and Levinson’s model and Blum-Kulka, House and Kasper’s framework as guidelines. To obtain the results, a discourse analysis was implemented. The AnConc software was used as a research tool for the study. 40 emails from 80 students were collected and divided into three types of requestive emails: assistance, confirmation and consideration, and recommendation for data analysis. Syntactical and lexical modifiers were examined and politeness markers were identified manually by the assistance of the AnConc software. The results indicated that Vietnamese students often used status-stating, deferent and solidary politeness strategies to approach their professors for personal requests. While using these three strategies, the target students had to use syntactical and lexical devices such as modals, interrogatives, please, and hedges as speech acts or supportive moves to gain their requestive purposes. The study also identified a common pattern that Vietnamese students liked to use the email corpus in the direction of salutation, self-introduction, requests, reasons for request, and thank compliments. The study has pedagogical implications for language teachers and learners; e.g. email writing should be taught to students, especially ESP students as these students do not know the format and the appropriate language they should use in email composition. Language students should also pay attention to the correct formal form and cultural differences when composing requestive emails delivered to their professors.