We reject anything whose mid does not include the fqdn or address literal of their sending server. We do this because the RFC says explicitly that the mid *MUST* have those features. We write exceptions for those few senders who are legitimate but have lazy and incompetent sysadmins.
On Mon, Jan 1, 2018 at 00:15, Mark London <m...@psfc.mit.edu> wrote: Message-ID: <NTMHDCrauhrQ5zjWNWEB20SB8wSA1X00000533@NTMHDCWEB20SB>
