[RCU] ext-mx01.kolabsys.com lists.roundcube.net delivery problems encountered

Simon Loewenthal simon at klunky.co.uk
Wed Nov 27 15:21:08 CET 2013

I would not use smtp-auth because my mail server is simply relaying a 
mail to them.

I think I noticed this happening when my mail server sends mail to 
ext-mx01.kolabsys.com, because mail is accepted if sent via 

Here are the headers from the email that was bounced, and here we see 
the From set to users at lists.roundcube.net upon reply, and now I know 
exactly why this happens!    I have a Roundcube plugin installed called 
"When replying to an e-mail sent to you through an address not in your 
identities list, plugin will automatically fire and set "From:" header 
to the address the original e-mail was sent to."

MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8;
Content-Transfer-Encoding: 7bit
Date: Wed, 27 Nov 2013 13:23:56 +0100
 From: Roundcube Users mailing list <users at lists.roundcube.net>
To: users at lists.roundcube.net
X-Sender: users at lists.roundcube.net
User-Agent: Roundcube Webmail/0.9.5

This explains everything :)

On 2013-11-27 14:54, Benny Pedersen wrote:
> Simon Loewenthal skrev den 2013-11-27 14:22:
>> said: 553 5.7.1 <users at lists.roundcube.net>: Sender address rejected: 
>> not logged in
> the above error is that you either use there domain or not using smtp 
> auth
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> users at lists.roundcube.net
> http://lists.roundcube.net/mailman/listinfo/users

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