we encountered a problem which I can't reproduce. (At least) two times it happened that a mail was sent with Outlook and Zimbra Outlook Connector. The mail is synchronized to the "Sent" folder but the mail wasn't sent at all. Also in the logfiles I haven't seen ANY communication for that mail. Normally you can track every step from receiving, scanning up to delivering the mail in the logfiles. But in this case there is NOTHING for that single mail.
It happened for two different users. And in one case the user was sending another mail just 1 minute later which did arrive and is written correctly in the logfiles.
The server version in the first case was 4.5.5 (as well as the Zimbra Outlook connector). In the second case it was the 4.5.10 server with a 4.5.5 connector.
If you check the sent folder with Zimbra web you also can find that mail. So seems the synchronisation is working however by any reason the mail was not sent.
Has anyone had the same problem? What do you think could be the reason for this? Maybe the internet connection was failing for sending and short after synchroistaion was working but Zimbra didn't recognize the mail to be sent anymore...
Hope this never happens again.