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Re: gmail dropping mesages
From: Jeff Mitchell <jmitchell () ll mit edu>
Date: Mon, 25 Apr 2011 13:12:08 -0400

On 04/22/2011 07:24 PM, Lynda wrote:
Non existent, it's SPF only.

My point.

Nearly all of the spam I see is DKIM signed. It just makes messages
bigger. I'd just as soon our volunteers spend their times on other
things, myself.

DKIM isn't designed explicitly to stop spam, it's designed to identify senders.

If you trust the issued certificates(!) being used to sign the mail, you at least have a good indication that the spam is coming from the domain that it says it's coming from. This can make spam blocking much more effective because instead of simply hoping that a domain-based blocklist will block spam and not ham (due to spoofed sender addresses), you have a pretty good feeling that this will be the case.

Of course this relies on various other bits and pieces to fall into place, such as properly handling such messages (Gmail's detection and handling rules aren't public AFAIK), CAs not being compromised, etc. Not to mention that the spammers can simply register another domain and buy a new cert -- but then the argument above still holds.

--Jeff


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