Custom backend POP3/IMAP/SMTP Server

We are in need of someone to develop a backend POP3/IMAP/SMTP server. All three protocols need to be able to operate on standard ports including 587 for SMTP and need to have both plain and SSL/TLS ability. We don't mind if an existing product, such as Dovecot is used and altered to be able to work with the backend system. Emails will be retrieved from a MySQL backend database. How it gets the mail files to the user is up to you as long as it's not sloppy. Authentication also comes from the database. The SMTP server needs to authenticate, send message, and then insert data into the database. Currently an API exists where the frontend can make calls to retrieve, set, etc. Open to suggestions if necessary. *Security is a must *must run on a linux or bsd system.