Hello,
Referring to my initial email and the followed comments I would like to
express the reason of why exactly this behaviour is needed to reject
spam. Well, the only other option is to send DSN. However the DNS may
end in a spamtrap/honeypot, thus blacklisting your MTA, just because it
sent DSN. This is a real disaster I had to experience, as spamcop
blacklists servers, who bounce spam messages.
So the schema
> if all rejected
answer "CR LF . CR LF" with 5xx
else if all accepted
2xx
else
2xx, and send a DSN with the exact details
is not at all an option. Moreover doing temporary rejects for all but
one recipient means practically applying grey-listing, with all it
delays and is not an option at all. At the same time I do not expect
that the spammer's SMTP servers will ever implement PRDR, so my vote
goes for
S: 550 Mail rejected for mailing-list(_at_)example(_dot_)org
except the server supports PRDR. Are there any better ideas?
Със здраве,
Дилян