Re: Stopping sendmail from relaying mail for user%somedomain.com@mydomain.com

From: Glynn Clements
Date: Sat Mar 27 2004 - 09:26:44 EST



Santosh Narayanan wrote:

> I use sendmail 8.11.6 on a Redhat Linux system (kernel 2.4.20). I find that
> even with relay checking enabled, sendmail is relaying email for addresses
> which are formatted as follows,
>
> To: user%somedomain.com@xxxxxxxxxxxx
>
> where "mydomain.com" is my local host name.
>
> If someone were to try relaying email to user@xxxxxxxxxxxxxx - it is
> rejected as per my relaying rules. But if someone uses the "%" technique it
> passes through the relaying rules and gets relayed anyway.
>
> I would appreciate any help I could get in preventing sendmail from doing
> this (perhaps even by completely stop accepting "%" in the recipient
> field?).

Was your sendmail.cf built with FEATURE(loose_relay_check)?

loose_relay_check
Normally, if % addressing is used for a recipient, e.g.
user%site@othersite, and othersite is in class {R}, the
check_rcpt ruleset will strip @othersite and recheck
user@site for relaying. This feature changes that
behavior. It should not be needed for most installations.

--
Glynn Clements <glynn.clements@xxxxxxxxxx>
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