How to stop a cascade of mail delivery failure messages

[Travis Roy]

 From what I understand the most you could get with sendmail is a double 
bounce, then it just starts throwing them away.

Any way to get a copy of the logs? You could blackhole the other 
server's IP address for 4 days until that auto-retry (default) expires 
and that should stop the ping-pong effect.

> A client seems to have a situation whereby a forged,
> and invalid, address in their domain was used to send
> out spam. Some of the recipient addresses are also
> bogus and therefore cause a mail delivery failure.
> This bounces back to the invalid user on their mail
> server and causes another mail delivery failure back
> to the original recipient's system. I'm getting the
> impression from my client's description that this
> bouncing back and forth is not stopping at this point
> but rather is continuing.
> 
> So first let me ask, does sendmail actually work this
> way, with no limit on ping-pong bounces? If it does
> then there must certainly be a way to stop it, such as
> silently dropping failed mail. I'm going to guess that
> a tweak to sendmail.cf will do the trick and am off to
> research that. I figured I'd check with the group as well
> just in case I can learn even more about the situation,
> which is usually the case with this bunch!
> 
> Thanks!
>