We have a working exim setup at a site, where users can send and receive mails. We are trying to setup a server to send some warnings and errors using email to an address that is outside the local network.
The problem is:
The program that sends the mails sends them using the username it runs under and the local hostname of the server. This cause the mails to have a sender of format: email@example.com. Exim sends these mails to the ISP's SMTP server, which rejects the mails as they have an illegal or unverifiable sender (the internal address).
I'm thinking I should configure exim to rewrite the sender when:
- sender's domain is on the local network
- receiver's domain is outside the local network
I tried setting some kind of rewriting in the exim config, but did not manage to get it to work. I'd show what I have tried, but I ran out of time on the last visit to the site, and had to revert to the original version losing all the changes I tried.