I have set the "Relay MTA for external delivery" in the admin GUI to the SMTP server of my ISP. Zimbra accepted this setting with no problems at all.
But when ever I send out an email, and I check the headers of the message at the "other end", it is not going via the ISP's smarthost. It always goes via the domain of the sending address : eg send from firstname.lastname@example.org and it always goes via mail.example.com even when Relay MTA is set to smtp.isp.com.
I have tried it both with and without the tick in "Enable DNS Lookups" but it does the same thing.
I have searched the forums and while ther are a few threads about problems with outgoing mail and relat servers, I can't find any that mention mail going via the wrong server.
Thanks fopr any help.