On Sat, Aug 30, 2003 at 11:49:40PM +0000, Brian May wrote: > On Sat, Aug 30, 2003 at 04:01:19PM +1000, Russell Coker wrote: > > > That is the idea behind autorespoonders after all, to tell the sender > > > that his mail didn't get through because it didn't meet some required > > > criteria. > > > > A SMTP 550 code can convey all the information that is needed for bounces. > > There are two problems with this. > > 1. The modular design of SMTP agents like postfix do not allow > scanning of messages before the message has been accepted by the > MTA at the SMTP session. I think you would have to add hooks > into smtpd, but that is going to complicate the code.
not true. postfix header_checks and body_checks check the message *before* it is accepted by the MTA. if it fails the test, a final 5xx reject code is issued rather than a 2xx "accepted" code. recent experimental versions of postfix also allow the same thing to be done with content-filters, although use of this feature is not recommended by Wietse due to the time it takes for a filter like spamassassin to run - there is a risk of smtp timeouts, especially on busy servers. > 2. All checks have to be automatic, and there is no chance of manual > review to ensure that the messages where geniune before bouncing it. > > The list of known solutions follows: > > (nil) actually, the known solution is: - reject if you possibly can, tag and deliver otherwise. craig