So yes, this may be an example of an SMTP relay violating RFC-5321. The
quote above was from a paragraph in 5321 talking about recipient addresses,
The quote in question is from section "2.3.11 Mailbox and address" and that's
under the SMTP terminology heaing. It is in no way specific to recipient
The way I read it, it seems to be saying "If you are not sure about a
local-part, don't try to be helpful, just leave it alone."
I disagree. I don't think that's a reasonable interpretation.
If I were the agent in charge of this "autoforwarder", I wouldn't even
read 5321 on this question. I would be quite sure of my policy on return
But the fact of the matter is others can and do read and apply it.