SpamAssassin fails to verify a valid DKIM signature

martvefun · 11-26-2012, 06:49 AM

I have installed spamassassin on my debian machine to verify incoming dkim signature (package spamassassin and libmail-dkim-perl). I use postfix and maildrop on virtual maildir mailbox.

I send an email from a Gmail address (which is supposed to have a valid DKIM signature) and the headers of my email contains that :

Code:

X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mart.ovh.net
X-Spam-Level: 
X-Spam-Status: No, score=0.5 required=6.0 tests=DKIM_ADSP_CUSTOM_MED,
	FREEMAIL_FROM,NML_ADSP_CUSTOM_MED,RCVD_IN_DNSWL_LOW,SPF_PASS,T_DKIM_INVALID
	autolearn=no version=3.3.1
X-Spam-Report: 
	* -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low
	*      trust
	*      [209.85.217.180 listed in list.dnswl.org]
	*  0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider
	*      (myemail[at]gmail.com)
	*  0.0 DKIM_ADSP_CUSTOM_MED No valid author signature, adsp_override is
	*      CUSTOM_MED
	* -0.0 SPF_PASS SPF: sender matches SPF record
	*  0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid
	*  1.2 NML_ADSP_CUSTOM_MED ADSP custom_med hit, and not from a mailing list

In my log spamd, I see :

Code:

Mon Nov 26 13:34:40 2012 [12995] info: spamd: connection from localhost.localdomain [127.0.0.1] at port 55274
Mon Nov 26 13:34:40 2012 [12995] info: spamd: processing message <50B361BA.8090007@gmail.com> for spamd:5001
Mon Nov 26 13:34:51 2012 [12995] info: spamd: clean message (0.5/6.0) for spamd:5001 in 10.6 seconds, 3117 bytes.
Mon Nov 26 13:34:51 2012 [12995] info: spamd: result: . 0 - DKIM_ADSP_CUSTOM_MED,FREEMAIL_FROM,NML_ADSP_CUSTOM_MED,RCVD_IN_DNSWL_LOW,SPF_PASS,T_DKIM_INVALID scantime=10.6,size=3117,user=spamd,uid=5001,required_score=6.0,rhost=localhost.localdomain,raddr=127.0.0.1,rport=55274,mid=<50B361BA.8090007@gmail.com>,autolearn=no

(by the way: the verification took 10sec, that's really long no ? I use spamc/spamd because it was supposed to speed up the verification)

I checked manually the signature of the email with opendkim and it succeed :

Code:

# opendkim -t - < /home/vmail/.../recievedemail 
opendkim: (stdin): verification (s=20120113, d=gmail.com, 2048-bit key) succeeded

When receiving an email, I use maildrop with the command

Code:

xfilter "/usr/bin/spamc -u spamd"

Any idea what can cause that ?
Thank you