Sendmail/LogWatch reports (may be forged)

Paul Howarth paul at
Wed Dec 7 18:43:29 UTC 2005

Timothy Alberts wrote:
> Thank you for the response Paul.
> I like the idea of blocking an IP range, as I'm already doing that for
> several spammers.  However, when I blocked on IP, they changed IP to
>  I could try and block multiple IP ranges, but it's just
> a moving target I think.  I block one and they move to another.  I don't
> want to have to play that game.
> So if sendmail finds that it can't trust the name (DNS fails in some
> manner), is there a way to configure sendmail to REJECT the mail as it
> is coming in based on failed DNS, rather than block IP ranges?

Technically this is possible, but you'll very likely find that you lose 
a lot of mail you actually want if you do that, since many sites still 
have broken rDNS.

You might have better luck using a blacklist, such as SBL-XBL 
( You can configure this in as follows:

define(`DNSBL_MAP',`dns -R A')dnl
FEATURE(`dnsbl',`',`"550 Mail from your server 
rejected - see" 

(the FEATURE is one long line)

P.S. Please don't top-post on this mailing list.


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