Re: [Exim] Ignoring bounce messages to alias - How?

On Fri, Feb 06, 2004 at 01:35:14PM +0000, Alun said:
> We've been getting a lot of bogus bounces here recently (and sending lots
> too (buf not to MyDoom, I hope!), but I've finally managed to get permission
> to turn that off!). It got me to thinking about what we could do about it.
> I've installed Tim's ruleset, but I was wondering whether something along
> the following lines would work in general.
>
> On outgoing mail, add a header containing a tag which changes every
> hour (e.g. MD5(secret . int(time/3600)))
>
> Keep a list of recent (say a month's worth?) tags that have been used.
>
> When a message from <> comes in, search it for any used tag and, if not
> present, drop the bounce.
>
> You could go further and make the tag cryptographically dependent on
> the message ID or something, but I think it would be best to keep the
> search simple.

Why go through all the bother of the MD5 when you could just search for
the message ID... If the included (not main) message ID doesn't match
the pattern your servers generate, drop it. You don't even need to keep
a record of message ID's - just the pattern.

Don't have an answer about % of mailers that don't include full
headers...