[ExchangeList] Re: SPF and External to External Distribution List

  • From: David Sierra Fernández <SieFerDa@xxxxxxx>
  • To: "exchangelist@xxxxxxxxxxxxx" <exchangelist@xxxxxxxxxxxxx>
  • Date: Thu, 7 Oct 2010 19:17:26 +0200

Yes the list have our own domain name in the SMTP address.

 

We have SMTP address lists like list@xxxxxxxxxxx (imagine contoso as our exchange domain) . A user of gmail  user1@xxxxxxxxx  write to the list and in the list there is a contact member (user2@xxxxxxxxxxx) . This hotmail user would receive a mail from gmail user but the gmail server detect that it was sent by a CONTOSO mail server. The normal situation is that hotmail drop the message or at least mark CONTOSO as a potential spammer.

 

Up to now we solve this thanks to other mail server (Critical Path) rather than Exchange that changes the envelope FROM address of all the list with a generic address (contoso-owner-list@xxxxxxxxxxx). As a result the hotmail user notices that the sender is the gmail user but gmail servers perfectly detects that the mail is sent indeed by CONTOSO servers and don´t drop the mails.

 

We are going to deprecate the old mail server and migrate de lists to exchange. The first tests have not been successful at all. We have no way to tell destination servers that the mail comes from gmail but we are not impersonating but only relying.

 

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David Sierra

Messaging Administrator

JCYL (Spain)

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De: exchangelist-bounce@xxxxxxxxxxxxx [mailto:exchangelist-bounce@xxxxxxxxxxxxx] En nombre de Chris Wall
Enviado el: jueves, 07 de octubre de 2010 18:40
Para: exchangelist@xxxxxxxxxxxxx
Asunto: [ExchangeList] Re: SPF and External to External Distribution List

 

I would assume that your DL’s have your own domain name in the SMTP address.  If your DL’s are not assigned your SMTP domain that is listed in your SPF, then of course they will fail.

 

Are you assigning different SMTP Alias’/domain names to your DL’s than what you actually host?


Regards,

Chris

 

From: exchangelist-bounce@xxxxxxxxxxxxx [mailto:exchangelist-bounce@xxxxxxxxxxxxx] On Behalf Of David Sierra Fernández
Sent: Thursday, October 07, 2010 12:27 PM
To: exchangelist@xxxxxxxxxxxxx
Subject: [ExchangeList] SPF and External to External Distribution List

 

Hello,

 

Perhaps some of you have this scenario in your exchange organization and I would like to know how you accomplish it:

 

·         We have exchange distribution lists with external members (contacts)

·         Other external users write to these list

 

The result is that out domain is sending mails impersonating an external domain. If destination domain use SPF (as we do) will drop down the mails believing we are spammers.

 

How do you solve this situation?

 

Thank you very much for your help.

 

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David Sierra

Messaging Administrator

JCYL (Spain)

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