On Wed, 12 Apr 2006 10:16:53 PDT, Steve Thomas said:
I haven't seen any succinct justification for providing a 550 message rejection for positively-identified spam versus silently dropping the message. Lots of how-to instructions but no whys.
RFC 2821?
...the protocol requires that a server accept responsibility for either delivering a message or properly reporting the failure to do so.
Elsewhere in 2821 (6.1, to be specific): When the receiver-SMTP accepts a piece of mail (by sending a "250 OK" message in response to DATA), it is accepting responsibility for delivering or relaying the message. It must take this responsibility seriously. It MUST NOT lose the message for frivolous reasons, such as because the host later crashes or because of a predictable resource shortage. OK? Got that? You '250 OK' it, you got a *serious* responsibility. Losing the message because the whole damned machine crashes is considered a frivolous reason. And throwing it away because you don't like the way it looks is OK? Man, you're in for some severe karmic protocol payback down the road... ;)