OT: Sendmail REJECT or DISCARD preference

[Steve Freegard]

Peter Farrow wrote:
> If you reject,  and its spoofed you'll get it back anyway, so you end up 
> receiving and then storing it in the postmaster address, it is always 
> best to discard in this scenario...or even worse bouncing it again

Huh? - explain this a bit better as it doesn't make sense to me.

If someone is spoofing your MAIL FROM, then there are a number of ways 
to combat this without using DISCARD and it's associated disadvantages 
(SPF testing at SMTP time, milter-null, custom ruleset etc.).

Using REJECT in an access-map is no different to using DNSBLs at the 
SMTP phase and that doesn't cause this.

I would only personally use DISCARD in a couple of instances:

1)  To nuke junk from my own secondary MX to prevent it from generating 
backscatter.

2)  To prevent duplicated messages.

3)  To prevent any other sort of backscatter emanating from machines 
under my administrative control.

In all other cases I would send an SMTP level rejection, it's far less 
costly.

Regards,
Steve.