Quick and easy pop or imap server with Dovecot: "Picking up where we left off a while ago, let’s add yet another feature to our Ubuntu server. We’ve already looked at using Postfix with multiple topics (see Postfix on Ghacks). But we never discussed a means to deliver the mail from the server to the client. That will now change. Linux has multiple ways to deliver email to clients. One of the easiest (as well as most flexible) means is via Dovecot."