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Article: 465
From: Ryan Moore
Date: 2005-04-04 15:08:44 -0400
Subject: Re: Milter-sender How to deal with servers that reject

Removal...........: milters-request@milter.info?subject=remove
More information..: http://www.milter.info/#Support
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Emery Guevremont wrote:
> I recently started using milter, and I noticed that with some servers, 
> milter-sender can't verify the senders email address, because the mx for 
> the domain rejects the mail from address <>.
> Here's an example of the exact log message:
> 
> Milter: from=<rddi@uymail.com>, reject=550 5.7.1 MX 10 
> 'uymail-com.mr.outblaze.com.' [205.158.62.177] for <rddi@uymail.com> 
> rejected address saying "<>: No thank you rejected: Account Unavailable, 
> Possible Forgery"
> 
> And so since, milter-sender can't verify the sender, the mail is 
> rejected by my mx.
> 
> How should I handle this situation, without refusing emails?
> 


I usually whitelist the domains in the the access.db if they're trying 
to email a user on the system. I also send out an email the the 
technical contacts for the domain. I'll paste the email below that I 
use, any advice or other useful links would be appreciated as well (I 
only include that last little bit if they're using Imail, as indicated 
by the SMTP banner of their MX).


Ryan Moore
----------
Perigee.net Corporation
704-849-8355 (sales)
704-849-8017 (tech)
www.perigee.net

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       The problem is that the mail server for your domain doesn't
accept 'mail from: <>', or the null address. This is a problem because
we have software on our system that requires the sender's mail server to
accept that so it can verify the sender's address, if it can't be
verified the incoming message is rejected. There are other ISP's doing
the same thing and anyone at your domain would have problems with them
as well, such as:

http://sourceforge.net/docman/display_doc.php?docid=6695&group_id=1#s_null_sender

It is for this same reason that you may not get bouncebacks, because
all delivery status notifications are sent back to the sender using that
'null address', and since the server rejects that it prevents
legitimate notifications from working, as well as breaking RFC
compliance (see http://www.rfc-ignorant.org/policy-dsn.php).

In any case, there is an option in the mail server software that they
are using that their mail server admin must have turned on, the page
below describes how to turn that option off:

http://support.ipswitch.com/kb/IM-19980116-DD02.htm
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