> Do you have any idea whether this downgrading is deliberate or just an > automated consequence of the spammers being better at using ED25119 > signatures ?
Hi Andrew, I sadly didn't get too much details on why and at which point the reputation goes down. I know, that the involved MTA marks the ED25119 signature verification result (even though it isn't actually verified) with an explicit 'fail' instead of 'neutral'. Analyzing the DMARC reports we received from this MTA we saw that the overall DKIM result ended up as a 'pass' though. My assumption is that some SPAM filter then sees this results, can't make much sense of it and marks the mail as SPAM. Kind regards, Florian -----Ursprüngliche Nachricht----- Von: mailop <[email protected]> Im Auftrag von Andrew C Aitchison via mailop Gesendet: Mittwoch, 12. März 2025 11:56 An: [email protected] Betreff: Re: [mailop] Valid ED25119 DKIM signatures leading to worse SPAM reputation? On Wed, 12 Mar 2025, Bierhoff, Florian via mailop wrote: > Hello all, > > Thanks for having me on the list. I'm working for German BSI and am > one of the persons behind our technical guidelines concerning mail > security. > > In our guideline for mail authentication we require sending mail > servers to apply DKIM signatures using RSA (1024 or 2048 bit) and > ED25119. > > I know that validating ED25119 signatures isn't as widespread as it > probably should be, but I have recently been informed that some > receiving mail servers may even downgrade a mails reputation in the > case of an existing valid ED25119 signature, if they don't have the > capabilities to validate the signature. This even happens if the > ED25119 signature is accompanied by a valid RSA signature. Do you have any idea whether this downgrading is deliberate or just an automated consequence of the spammers being better at using ED25119 signatures ? -- Andrew C. Aitchison Kendal, UK [email protected] _______________________________________________ mailop mailing list [email protected] https://list.mailop.org/listinfo/mailop _______________________________________________ mailop mailing list [email protected] https://list.mailop.org/listinfo/mailop
