I manage a domain xyz.com for which relaying to outside addresses is disabled. However, I get a lot of spam coming with the from: being users of the internal domain.
subject: I've got an offer for you that you can't refuse! :P
I use port 465 to support external, authenticated access to the MTA.
Is there any way I can force mail sent "presumedly" from the internal domain to be rejected on port 25 and thus only get them from the authenticated port ?