My website uses Exim to send contact forms via email. I migrated our mail servers to Exchange on a different server.
Our MX record is pointing to the new server and incoming and outgoing email works perfectly. However, the contact forms on the website still send the emails to the localhost. How do I configure Exim to not accept mail locally, but just relay it on to the MX record for the domain?
Exim is delivering locally because the destination domain matches one that you've configured Exim to consider local. Smarthosting doesn't come into it because that only kicks in once Exim's decided to route the e-mail somewhere else, and that's not what's happening.
The easiest way to handle this to grep through your Exim config for your domain(s) and remove them.