[ On Saturday, June 25, 2005 at 08:05:36 (-0500), Rick Cooper wrote: ]
> Subject: RE: [exim] a large number of domains fronted by Exim are refusing bounces...
>
> I have several addresses that never, ever, send mail. In fact I have an ACL
> that will catch any attempt for one of these accounts *to* send mail. I fail
> to see how there could be a valid reason for any system to send mail to one
> of these accounts with a null sender.
As Philip said though all mail destined to such addresses probably
conforms pretty closely to various rules unrelated to the sender address
and so there's no need to use the sender address when implementing
policies which control what mail can be accepted to those addresses.
> And then there are those systems that send "you sent a virus" bounces out
> from a null sender. If a system sends a message from null with a subject of
> "our antivirus... or your mail contained a virus, or virus detected,..." why
> should I accept it?
You shouldn't. However once again that has _nothing_ whatsoever to do
with whether or not such messages arrive with a null return path.
You shouln't accept such messages no matter what their null return path
is and thus there's no need to use the sender address when implementing
policies which reject such messages. These kinds of policy
implementations are are what I've referred to generically as content filters.
Using the fact that a message arrives with a null return path to
implement a policy which might result in that message being blocked
almost certainly means that your other policies and/or their
implementations are incomplete and insufficient. You should not ever
have to use the fact that a message has arrived with a null return-path
to block that message.
--
Greg A. Woods
H:+1 416 218-0098 W:+1 416 489-5852 x122 VE3TCP RoboHack <woods@???>
Planix, Inc. <woods@???> Secrets of the Weird <woods@???>
