I have accidentally learned that a postfix server has accepted and attempted to deliver an email with the envelope sender containing 8 bit ascii codes (it looks like this T\▒\▒m...@domain.tld - that's a backslash and then ascii extended code 177). the imap backend - an old cyrus lmtp service - has refused the delivery.
what rfc defines this? I am trying to 1) understand if postfix in cause (2.9.6 on debian wheezy) did the right thing to accept that email and 2) how to refuse such emails until I can upgrade the cyrus backend to permit such sender addresses. Note that I am only _guessing_ that the original message was sent using rfc822 format, as I can't find original nowhere in the queues; by looking at the bounce sitting in the queue (it was probably a spam) and seeing this header: X-Postfix-Sender: rfc822; "T\▒\▒..."@domain.tld
