This is a new Zimbra install with the latest version of Zimbra network and the outlook connector. The client is sending email from inside of peachtree and this crashes peachtree or freezes the machine. I found a bug with our problem but it says it was fixed in an older version of zimbra...we are having this same problem. Outlook 2007 SP2.
Bugzilla – Bug 26730
Bug 26730 – can't send via Send To -> Mail Recipient