Thank you for your time and the investigation.
There seems to be no solution on exim side.
I've whitelisted yahoo for the moment.
all the best.
Karl-Heinz
On 23.09.2014, at 14:22, Lena@??? wrote:
>> From: Karl-Heinz Wild
>
>> i've a problem with dkim and yahoo.
>>
>> the log shows me something, it seems very special
>> -----------------------------------------------------------------
>> 2014-09-23 12:00:06 1XWMtC-000Dzw-0C DKIM: d=yahoo.com s=s2048 c=relaxed/relaxed a=rsa-sha256 t=1411466404 [verification failed - signature did not verify (headers probably modified in transit)]
>> 2014-09-23 12:00:06 1XWMtC-000Dzw-0C DKIM: d=yahoo.com s=s1024 c=relaxed/relaxed a=rsa-sha256 t=1411466404 [verification succeeded]
>> 2014-09-23 12:00:06 1XWMtC-000Dzw-0C DKIM TEST: domain=yahoo.com possible_signer=yahoo.com status=fail reason=signature_incorrect
>> -----------------------------------------------------------------
>>
>> as you can see there are two lines. one succeeded and the first fails.
>> the difference seems to be the s=1024 vs s=2048.
>
> I just sent a few test messages via yahooMail ( @ yahoo.com ).
> Messages sent from a MUA (Opera Mail, like Thunderbird) in Eastern Europe
> via SMTP through smtp.mail.yahoo.com (with authentication)
> came from yahoo's datacenter in Ireland (nm14-vm7.bullet.mail.ir2.yahoo.com),
> each message has two DKIM-signatures: top one s=s2048 verification failed
> and bottom one s=s1024 verification succeeded.
> Messages sent from yahooMail's web-interfaces (Basic and FullyFeatured)
> came from yahoo's datacenter in Buffalo,NY (nm5-vm0.bullet.mail.bf1.yahoo.com),
> have only one DKIM-signature with s=s1024.
> Verification done by my Exim 4.83.
>
> I found an older message (05 Jul 2014) submitted from Thunderbird in Argentina
> via SMTP through smtp.mail.yahoo.com, it has two DKIM-signatures and came from
> yahoo's datacenter in Nebraska (nm10-vm4.bullet.mail.ne1.yahoo.com),
> so perhaps submitter's geolocation is irrelevant.
>
> I suspect that yahoos broke something when they did another stupid thing:
> mow messages submitted via SMTP don't show submitter's IP-address anywhere
> in the header (though messages submitted via web-interfaces do show
> submitter's IP-address in the bottom Received).
>
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