[Dovecot] Multiple authentication backends

[Wouter van der Schagt]

Good morning,

I have a question. Currently we are using Dovecot to handle our pop3, pop3s, imap and imaps connections. Our virtual domain management backend is vpopmail. Which works beautifully. Our current setup requires users to login with their email address and password (user at domain). 

We are now looking at migrating another server to our environment where users are logging in with their username only. This is because unlike virtual users these mailboxes have corresponding system users on the server. 

Ideally we would like to migration for the end user as easy as possible without requiring them to make changes to their settings. Is it possible to configure Dovecot to handle multiple authentication back-ends or do any of you have found a solution to a similar problem before?

Sincerely,
- Wouter van der Schagt