Yes, I use Symbiosis from Bytemark and run it on one of their BigV machines - Symbiosis wraps exim and dovecot for one of the easiest to manage virtual mail sys

Yes, I use Symbiosis from Bytemark and run it on one of their BigV machines - Symbiosis wraps exim and dovecot for one of the easiest to manage virtual mail systems I've ever run - all the Symbiosis "wrappers" around the various products are all open source as well.