Good day to all!
Weve just recently deployed/migrated from an old postfix to Zimbra and went well, although we received some reports of a relatively high spam incidents from our users.
Browsing over the wiki and forums, we were able to reduce the said spam incidents and SA trainings seem sufficient.
Recalling our old mail system, we have low spam incidents, due to ASSP i guess.
On a test lab, I setup a similar setup.. Zimbra and ASSP on the same machine.
- changed Zimbras smtp to 125
- configured assp to listen to 25 and smtp destination to zimbras custom port (125)

Upon testing, we were able to received mails, although upon hitting reply.. weve got an smtp error.
What seems to be the problem with this setup?