Yeah, sorry I meant as a soln for when your backend MX actually is *your* backend MX. That is, it knows it hosts the mailbox for localpart@example.com and the m

Yeah, sorry I meant as a soln for when your backend MX actually is *your* backend MX. That is, it knows it hosts the mailbox for localpart@example.com and the mail recipient address matches on the envelope. I understand the vagaries wrt forwarding to an acount of a different name and you're spot on there.