I opened a support case with Zimbra first and they qualified it as a bug.
Bug 59217 – SMTP Milter timeout
There has been no work on it though and no commitment to fix.
well, is a very annoying bug, multiple clients of mine use outlooks and thunderbirds and all of them have trouble when they send attachements bigger than 3MB.
Make sure you vote on the bug and leave a comment about how it is impacting you. That is the only way we can get it fixed at this point.
It really is interesting that there has not been that much complaining about this issue. Either not that many people use Fat email clients outside their fast LAN network or nobody is sending attachments..
confirmed that if you turn off the zimbra milter system goes back to normal, no problems attaching files, but i dont have distribution list security without that.
I have the same issue. Does anyone find a solution?
If i turn off milter, messages go normaly. if turn on messages bigger then 4 MBs do not are send.
I`ll write at the bug report.
Everybody still with the same problem?
Seems to be a timeout between the milter server and postfix. When the cleanup server pass throught the conections it cuts off them.
We solved it adding:
Let us know if this solve it for you
I have same problem when milter is on we are unable to send 3 to more mb attached file in outlook express