SMTP is easy. POP3 is easy. IMAP is more complex. Building a simple email client (say, like mail(1), even including SMTP and POP3 instead of local delivery) i

SMTP is easy. POP3 is easy. IMAP is more complex. Building a simple email client (say, like mail(1), even including SMTP and POP3 instead of local delivery) is rather easy. It could be a nice programming project for first year (2nd semester) students, I'd say. Of course, you can complexify things, adding GUI, IMAP, MIME, displaying inline attached files (pictures, pdf files, etc), SSL/TLS, dealing with local mail folders, spam filters, automatic mail sorting, including an wysiwyg editor, message encryption with key management. But the basic mail(1)-like client using SMTP and POP3 is easy.