Clean install on FC3 (minimal then added curl, libidn & fetchmail). All appears to be working. Mail sent out from Zimbra web client gets received. Mail sent to itself gets received.
Mail from outside Zimbra does not get received. MX record is mail.csiyk.com. Zimbra server hostname is zimbra.csiyk.com. Default domain on server is csiyk.com.
Must be missing something. I have not changed anything from defuals other than disabled non-secure items (ie only SSL for POP and IMAP). I think my problem is with MTA settings. Default web mail MTA is "localhost".