On Sun, Mar 28, 2004, Claus Färber wrote:
Claus Assmann <ietf-smtp(_at_)esmtp(_dot_)org> schrieb/wrote:
It seems you want LMTP, at least its RCPT replies after the final dot.
Someone should specify this as an ESMTP extension...
An SMTP extension would simply not be used by spammers.
You can, however, only allow one recipient at one time (and temporarily
reject all subsequent RCPTs) when the extension is not in use.
So why not offer the extension such that it can be used by well-behaved
MTAs? For spammers (unknown hosts or hosts that don't use the
extension) you use the second method (accept only one recipient).
This will at least help filtering if the mail is relayed via the
MTA of the ISP which should be easier to upgrade to support the
extension.