Re: [EXIM] Relaying

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Author: Jeffrey Goldberg
Date:  
To: Steve Lamb
CC: exim-users@exim.org
Subject: Re: [EXIM] Relaying
On Thu, 29 Apr 1999, Steve Lamb wrote:

> On Fri, 30 Apr 1999 00:27:58 +0100 (BST), Robert Baskerville wrote:


> >> relay_domains_include_local_mx = true
>
> >Doesn't this leave you open to abuse though? Anyone can list *your*
> >system as an MX for *their* domain in their DNS....
>
>     Yeah.  If that is the case, why is it in there?


This has been discussed on the list before.

Using this doesn't leave you open to too much abuse if you keep on eye on
things somehow. Afterall, if someone sets you up as an unwilling
MX backup (which these leaves you open to), then they are far more
vulnarable than you are. You can hold their mail hostage until you get a
very very good explanation about what they did.

As for the utility of it, how often do you see bounces from sendmail sites
listed as MX which give 550s saying that don't relay for the site they are
the MX back-up for? I manage a couple of small/medium mailing lists and
get passed some queries from Cranfield users who get NDRs they don't
understand and see something like that about once a week.

While I don't use this, I think it is very useful, and the danger is very
limited.

-j

-- 
Jeffrey Goldberg                +44 (0)1234 750 111 x 2826
 Cranfield Computer Centre      FAX         751 814
 J.Goldberg@???     http://WWW.Cranfield.ac.uk/public/cc/cc047/
Relativism is the triumph of authority over truth, convention over justice.



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