[Mimedefang] Greylisting Question

[David F. Skoll]

On Sun, 11 Jan 2004, Rick Mallett wrote:

> Sorry, that still isn't very clear. Let me try again. The question
> really is "in a given SMTP session does filter_recipient get called
> for each recipient of a given message regardless of the return status
> of any particular call to filter_recipient?".

Yes.  That's how SMTP works; the RCPT command is oddball in that the
response code applies _only_ to that recipient.  For all other commands,
the response code applies either to the entire message or the entire
SMTP session.

> If not, if the 451 error status is returned immediately in response to
> a given "RCPT TO" command, and if that terminates the session, then it
> would seem that the message will get tempfail'ed for the full blocking
> period, only to get tempfail'ed for another blocking period when the
> second recipient is finally encountered and so on and so forth.

No; it won't work like that unless the sending MTA is buggy and gives
up after the first RCPT is tempfailed.

Note that returning a 4xx code in response to RCPT most likely exercises
poorly-tested code paths in most MTAs, so beware...

Regards,

David.