On Sun, 26 Aug 2001, Lauri Tischler wrote:
> Suresh Ramasubramanian wrote:
> >
> > Also, see http://www.rfc-ignorant.org ... and if you are a large enough
> > site, blackhole the idiot domain. When their admin comes crying to you,
> > you can wave the relevant RFC in his face.
>
> The 'dsn.rfc-ignorant.org listing policy' says :
> <quote>
> "The syntax shown in RFC-821 for the MAIL FROM: command omits the case
> of an empty path: "MAIL FROM: <>" (see RFC-821 Page 15). An empty reverse
> path MUST be supported."
> </quote>
Yes, this RFC points out that the previous RFC forgot to include this
case - the case of an empty return path. It also says that an empty
return path (eg MAIL FROM:<>) MUST be supported.
> If I understand this right, the admin who is trying to protect his
> network fron unnamed spammers is made the villain.
>
> Why should anybody accept any mail without excisting from address.
> Immediately upon recieving a message, any sane MTA should check that the
> sender is valid, if not then dump the message.
The address <> *IS* valid, specifically as the sender for non-delivery
reports (aka bounces), so that bounces are not generated for
undeliverable bounces (to avoid mail loops).
The various RFC's are quite clear about this, and REQUIRE bounce
messages to be sent this way, and REQUIRE systems to accept them. Every
sane MTA DOES send them this way, and any system that rejects them is
rejecting all non-delivery reports for any mail its users send.
Anyone who thinks they are protecting themselves from spam by doing
this, is very misinformed - very little spam is sent this way.
