Re: Suggestion - regarding "Backscatter" (from another newsgroup)

D. Stussy wrote:

I do not argue directly pro or con your idea, but basically you try to
modify the mail transmission process into something like "cluster-mail-
processing". The downstream server (sendmail would need to differ
between downstream - aka internal - and external servers) is passing
back how to handle the message by sendmail by misusing the SMTP error
code. In the current idea of sendmail, I'd say, the downstream server
has to process the message and act accordingly, e.g. discard the
message itself.

Although I do not have no need for such thing, I would stay away from
the SMTP error codes alone, but hook on the comment, e.g.

550 5.7.1 Policy error

is a shared secret by the servers and the is
passed to a rule set or something like that.