DBMail is described as 'fast, scalable IMAP4 and POP3 server that stores all email and users in a Postgresql, MySQL or SQLite database' and is an app in the Office & Productivity category. There are five alternatives to DBMail for Linux, Mac, BSD and Self-Hosted solutions. The best alternative is iRedMail, which is both free and Open Source. Other great apps like DBMail are Dovecot (Free, Open Source), Cyrus IMAP (Free, Open Source), Archiveopteryx (Free, Open Source) and Courier IMAP (Free, Open Source).
A fully fledged, free email server solution, an open source project (GPL v2). Use official binary packages from Linux/BSD distributions, with both i386 and x86_64 support. Easy, fast deployment in LESS THAN 1 MINUTE. View YouTube Video to check how easy it is.
The Cyrus IMAP server differs from other IMAP server implementations in that it is generally intended to be run on sealed servers, where normal users cannot log in. Users can access mail through the IMAP/IMAP-S, JMAP, POP3/POP3-S or KPOP protocols.
Archiveopteryx is an Internet mail server, optimised to support long-term archival storage. It seeks to make it practical not only to manage large archives, but to use the information therein on a daily basis instead of relegating it to offline storage.