[NTLUG:Discuss] How to avoid mail loops?

[gan hawk]

Hi,

I think most programs like postfix add the Delivered-To field to keep track 
of the hop count. But yeah, a server can mess with the headers. In that case 
you need to have a count for the number of mail recived from external 
address and have a saftey feature to cut off once it reaches the threshold 
(server's maximum capacity). It will stop undetected loops and mail bombs.

You also have to filter bounce messages. Because even if there is no 
intentional loop but if the mail address which is used by user to forward 
the incomming mail, runs out of space and bounce all the messages, it will 
again create a loop.

Ganesh


>From: "Neil Aggarwal" <neil at JAMMConsulting.com>
>Reply-To: NTLUG Discussion List <discuss at ntlug.org>
>To: "NTLUG" <discuss at ntlug.org>
>Subject: [NTLUG:Discuss] How to avoid mail loops?
>Date: Sun, 22 Feb 2004 20:09:35 -0600
>
>Hey all:
>
>I am working on an email service where users can forward
>their incoming email to another email address.
>
>I just realized that this can easily lead to a mail loop
>and consume all of the resources of the smtp server if that
>email account forwards the mail back to the email account
>it came from.
>
>I have considered marking the messages with a header somehow,
>but that depends on the remote server giving me back that
>header.  If it doesn't I have no way to detect the loop.
>
>Any ideas how to avoid this problem?
>
>Thanks,
>	Neil
>
>--
>Neil Aggarwal, JAMM Consulting, (972)612-6056, www.JAMMConsulting.com
>FREE! Valuable info on how your business can reduce operating costs by
>17% or more in 6 months or less! => http://newsletter.JAMMConsulting.com
>
>
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