Did an upgrade last week from Ubuntu 12.04, 8.0.1 to 8.0.3. As the week went on had some complaints from people inside the company that they were getting Access Denied messages when sending mail. Checked outlook settings and not even really thinking just added the outgoing server requires authentication because that is the default setting in our company for everyone. Oddly enough as the week went on people that were working fine started seeing the issue. I thought it was an Outlook problem. Yesterday I got a call from a remote webmail user saying he was having a problem. I could easily replicate with any account through webmail all email outside of the company scope is getting relay access denied. Our internal servers that send nightly messages also broke yesterday after working all week. Digging through the zimbra logs I saw that the problem is that even though I have our whole network trusted, zimbra isn't allowing unauthenticated email through it as it always has. Tried multiple things to correct the problem including disabling ipv6 removing all trusted networks and re-adding them, etc. Running out of ideas.