We're currently looking into using the Professional version for a few projects. So far we are very satisfied with the way things work, however, there are some questions remaining: Can the "Relayed Domains" under "Mail Proxy" be specified as an LDAP query? Since the domains to relay mail for would be quite dynamic, it's not feasible to list them all here. Can SMTP transports be specified per user from LDAP? The idea would be to deliver mail for user email@example.com on server X and mail for user firstname.lastname@example.org on server Y. The users can thus be in the same domain, but their mail would reside on a different server. In practice, user a could be on an Exchange, user b on a Dovecot IMAP box. Can the quarantine be accessed through an API or anything similar?