Hector Santos wrote:
I have to see if our GL people are comfortable enough with GL to justify
adding a RCPT TO rejection option.
[Aside: I think "General Ledger" when I see GL... but anyway...]
Tempfailing RCPT commands will cause interoperability problems with certain
broken SMTP implementations, specifically ones from Lotus. Here's what
happens. S is the server doing greylisting and C is the broken Lotus client:
S: 220 foo.example.com ESMTP
C: HELO busted.lotus.box
S: 250 foo.example.com Hello busted.lotus.box
C: MAIL FROM:<bob(_at_)example(_dot_)net>
S: 250 Go ahead
C: RCPT TO:<jane(_at_)example(_dot_)com>
S: 451 Greylisting in effect, try again later
C: RCPT TO:<bill(_at_)example(_dot_)com>
S: 451 Greylisting in effect, try again later
C: DATA
S: 503 Need valid recipient first
C: QUIT
at which point busted.lotus.box generates a non-delivery notification.
Sad, isn't it?
Regards,
David.