I have an odd problem happening. A person is sending us mail, and that person has an apostrophe in her e-mail address. If the message is first routed through our Barracuda, then through the Zimbra OSS box, it never arrives, and the sender gets a 'mailbox is unavailable' NDR. If the message is routed directly to the Zimbra box (bypassing the Barracuda), then it arrives fine.
I tested this by telnet'ing to each (Barracuda, then Zimbra) and using the following message test:
subject:Test with apostrophe 5:30
With the above test, the message sent through the Barracuda shows as having been processed by the Barracuda and sent on to the Zimbra box, but produced the NDR. The message sent directly to the Zimbra box went through without a problem.
Is there any known interop problem between Barracuda (or other spam firewalls) and Zimbra? I will say that having an apostrophe in an e-mail address is pretty stupid, but we can't control this because the sender is outside our domain.