When sending out emails with postfix I sometimes get this error:
451 #4.1.8 Domain of sender address <firstname.lastname@example.org> does not resolve (in reply to MAIL FROM command)
mydomain.tld is resolvable though, meaning A, MX, PTR records are set properly.
However, the sending server does have a different domain
anotherdomain.tld but it is allowed to send emails from
mydomain.tld since I set the MX records of
anotherdomain.tld. The envelope from of the problematic emails is
Is there some other dns entry I have to set?
Or how else could I solve the problem? (I would like to keep the server structure though)