Re: SA DKIM related bug 6462 - Possibly Gmail, Sendmail and/or Thunderbird related?

From: SM <sm_at_resistor.net>
Date: Thu, 15 Dec 2011 15:44:41 -0800

At 15:25 15-12-2011, Kevin A. McGrail wrote:
>Specifically, the case change on the To: header.
>
>So what rewrote the To: header and why?
>
>The one thing I've been able to pin down is that if I use the gmail
>web-based interface and play around with case, the for part of the
>received header has the correct case and my DKIM tests work fine.
>
>However, when AXB uses thunderbird to send via gmail, the case
>sensitivity between the for in the received and the To header
>appears different.
>
>
>Now on a pure sendmail environment on a stock CentOS Installation,
>attached is an email AXB wrote via Thunderbird sent via gmail. Note
>that it will fail opendkim UNLESS you modify the to header to the
>correct email address he used to root_at_TALON1.PCCC.com. Somewhere
>along the way the To: header gets rewritten to all lower case.
>
>However, I couldn't reproduce this scenario with all my tests but I
>don't use anything but Gmail's web interface.
>
>So my conclusion is that Thunderbird or Gmail are somehow ending up
>with one case version of the to address as the for in the received
>header and a different case version in the to header. Then during
>delivery, either procmail or sendmail are "fixing" the To: header
>which is breaking DKIM.
>
>Anyone have any recommendations? Is this known behavior in sendmail
>or procmail? Something specific to Gmail and using an external client?
>Specific to Thunderbird?

Sendmail is not causing the problem here. I would also rule out a
Thunderbird issue. Can you test to see whether the domain gets
changed to lowercase when you send a message to Gmail?

Regards,
-sm
Received on Thu Dec 15 2011 - 23:48:00 PST