Re: [cobalt-users] Disable "postmaster@domain" adresses

[Lauchlin <lauchlin_list@xxxxxxxxxxxx>]

On 27/11/2003, at 11:27 PM, Graeme Merrall wrote:

> Quoting Ramon LOPEZ <r.lopez@xxxxxxxxxxxxxxxxxxx>:
>
> > Hello,
> >
> > How can i disable "postmaster@domain" adresses on a RAQ3 ?
>
> Short answer is don't. The postmaster address is an important 
> functional address
> for your email system. You may as well ask how do I remove the 
> 'nobody' or
> 'root' user.
> For information on postmaster addresses see
> http://www.faqs.org/rfcs/rfc1173.html.
>
> Some spam blocking lists (RBL etc) appear to include lack of postmaster
> addresses in the rating of your 'badness'
>
> Cheers,
>  Graeme

While I agree that it is important to stick to RFCs the problem is that 
the majority of postmaster accounts end up being a wonderful bin full 
of spam themselves.  On our RaQs I regect the worst cases with a 
message to the effect of something along the lines of the account being 
a spam trap and for problems please contact the owner of the net block. 
 All domains we host use mx hosts that do not have their domain name in 
them.  Probably not 100% RFC but it still leaves a way for someone who 
really needs to get into contact with us ways of getting to a valid 
address while saving on a lot of traffic and wasted cpu cycles sifting 
the spam.

Anyway, to do this the best way I have found is to

1) add:
	FEATURE(blacklist_recipients)
to your cobalt.mc file
2) rebuild your sendmail.cf
3) add:
	postmaster@xxxxxxxxxx      550 This e-mail address is a spam trap
or something similar to your access file
4) Re hash your access.db
5) Reload sendmail

If you are really nasty you can use ipchains or something to drop all 
routes to multiple offenders by writing a script that follows your 
maillog and looks for  the spam being rejected.  Personally I don't go 
this far. ;-)

Just remember to at least have one functioning postmaster 
account/address functioning on the server for as Graeme says it is an 
important part of the mail ing system.

Cheers,

--
Lauchlin Wilkinson
Internet Tasmania Pty. Ltd.