I installed Zimbra (community version) on a ubuntu 8.04 server on a clean system.
I following that guide:
How To Install Zimbra Collaboration Suite (ZCS) On Ubuntu | HowtoForge - Linux Howtos and Tutorials
After installing it, as it puts there, (the only thing I did was not put in the local DNS, but I have some external.
Well, after this, work out perfectly all the features of Zimbra, except .. receive the post, which moves directly to the Deferred queue, and error shows me:
connect to "mail" [xx.xx.xx.xx] connection timed out
But for another way, I can send emails perfectly.
Not to continue, ...
(sorry my bad english)