I have the split working the one way, so if I email the address
ticket@itas.ca it is delivers mail to the account on titan, but it is the outgoing email coming from titan that does not get delivered to zimbra (mail.itas.ca), but it is delivered to the internet.
MAIL to mail.itas.ca from internet works
MAIL from mail.itas.ca to internet and local zimbra accounts work
MAIL from titan.itas.ca to internet works
MAIL from titan.itas.ca to Zimbra server on same network does not work.