Is it possible to use one POP3/IMAP account for multiple users?
Of course it is, although we do not recommend it. This setup is known as a "catch all" account. Check the option "Send messages to the mail address found in their message header (catch-all account)" on the POP3 / IMAP account setup form to automatically forward the mail messages to the appropriate accounts. You can also create rules for every SMTP user to declare which mail should be forwarded to which address.