our internal mail server (with no internet connection) has had the option “Verify sender’s domain in DNS:” enabled for well over 6 months without a problem. we recently changed to active directory and it’s now rejecting messages from smtp users in one of our own domains, all other domains we use are working fine, the mail is accepted and relayed. i’ve run nslookup from the machine in question and the domain name can be resolved to the correct ip address. does anyone have any ideas where to look for this?
the domain in question used to be the domain the server was in previously before it joined the active directory at which time it changed domains