I've had a search about the forums for this, but haven't come across anyone either wanting this feature, or is so simple and blatantly obvious and I've completely missed it.

Basically, I have a few domains I administer, but a couple of them have their own mail servers which look after their own mail accounts, and I simply forward on mail for that domain via SMTP to their particular mail server. The benefit being that I don't have to manage the individual e-mail accounts, as that is performed by the other server, and if their server ever goes down, future inbound mail is kept on my server until their server is back up online and my server automatically spools out the mail to their server.

I'm doing this at the minute using postfix, specifying an smtp: entry in the transport table which works a treat, however I've not noticed anything in Zimbra that will let me easily do the same within the GUI. I've got no problem adding the entries back into the transport table in Postfix on the Zimbra server, but was worried that if I do that, A) are my changes going to be permanent, and B) it would be nice if I could administer this somewhere or at least see the domains I do this to in the admin GUI, as it will otherwise look like I don't have these domains set up at all, which might confuse anyone else that looks at the setup I've got.

Is this a feature which is already available in Zimbra or would I need to use the Network version, or even have to wait for something like this to become available?