Address and reference terms have attracted a lot of attention in sociolinguistic research. The present study contributes to these works by investigating the kind of address and referring expressions used by postgraduate students when they share e-mails with their lecturers and their colleagues as well as how age, gender and familiarity affect these terms. Using Brown and Ford’s (1961) study on Address in American English as a conceptual framework, a Discourse Completion Tasks (DCTs) questionnaire was designed and used to retrieve data from fifty-six (56) respondents who were all postgraduate students. The data revealed that postgraduate students mainly used five (5) forms of address terms in e-mails to lecturers: titles, attention getters, kinship terms, personal names and nicknames, and six (6) referring expressions (of lecturers) in e-mails to their colleagues: titles, kingship terms, personal names, nicknames, course titles and generic reference. The study concludes that, whereas age and gender greatly affect address terms and referring expressions in students-lecturers e-mails, familiarity does not present that much considerable influence on the address terms and referring expressions used in students-lecturers e-mails.