[Mailman-Users] cause of bounces

Stephen J. Turnbull turnbull.stephen.fw at u.tsukuba.ac.jp
Thu Oct 19 02:36:31 EDT 2017

Grant Taylor via Mailman-Users writes:

 > I use DKIM validity as a signal that I then make decisions based on. - 
 > Hence why I have chosen to alter spam score on my mail server based on 
 > the DKIM result.

You can do that.  But call it what it is: a deliberate decision NOT to
conform to a standards-track RFC.

The fact of the matter is that the spammers are laughing at you.  THEY
have perfectly valid DKIM signatures, or if they're going to try a
replay attack, they remove the DKIM signature they're about to break.
Broken DKIM signatures principally mean somebody added a footer to the
body, a DMARC mitigation in From, or a tag to the Subject.  So this
rule primarily targets perfectly legitimate mail posted to mailing

(I don't understand Dimitri's claim about SourceForge ads; all the
mail I get from SourceForge is originated there and AFAIK the DKIM
validates.  If it doesn't, their system is pretty brain-damaged.)


Associate Professor              Division of Policy and Planning Science
http://turnbull/sk.tsukuba.ac.jp/     Faculty of Systems and Information
Email: turnbull at sk.tsukuba.ac.jp                   University of Tsukuba
Tel: 029-853-5175                 Tennodai 1-1-1, Tsukuba 305-8573 JAPAN

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