Debug for "can't determine message sender"

From: Andrey Salnikov <fenidik_at_gmail.com>
Date: Fri, 24 May 2013 14:03:03 +0400

Hi

Its any way to debug "can't determine message sender" message?
I found dependence with mail client and getting "can't determine message
sender". All messages sent by Outlook isn't signed.
How I can grab headers from unsigned messages to fix this issue.

postfix 2.7.1
opendkim 2.6.8

Thanks
Received on Fri May 24 2013 - 10:03:16 PST