Re: [exim] Exim 4.72: preventing backscatter

On 08/27/2014 10:36 PM, Jeremy Harris wrote:
> On 27/08/14 16:11, Konstantin Boyandin wrote:
>> 2. Create 'catchall' router, intercepting all unrouteable addresses (I
>> think this is better solution).
>
> Don't. One type of spammer tries random names at your domain and logs
> for later use (and sale to other spammers) as "verified" any tha
> result in an accepted mail.

I see the point.

Our (company using Exim installation I talk about) policy is to accept
mail even from those hosts that do not implement SPF/DKIM/whatever else,
even in cases when mail is sent from an IP not verified by SPF and so on
- we have too many legitimate mail that doesn't pass those checks.

So currently I have 500 to 1000 of backscatter mail sitting in mail
queue, since it can't be delivered to forged sender of spam sent to
non-existing local addresses. Are there efficient ideas to reduce that
number?

I would appreciate any advice. Thanks.

Sincerely,
Konstantin