Le lun. 18 mai 2026 à 18:31, Tobias Fiebig via mailop <[email protected]> a écrit : > > Moin, > > fyi, i am currently debugging some deliverability issues with > outlook.com (mails queued, but seem to not be delivered). > > After getting my hands on an EML, i saw that the messages get > quarrantined, and show for a DKIM failure. > > The messages are triple-signed (SHA1, SHA256, ED25519).
Back in 2018, SHA1 has been banished from DKIM signatures, that protocol became way too weak and is now considered vulnerable. You must stop signing using SHA1 -> https://datatracker.ietf.org/doc/html/rfc8301#section-3.1 > The former two > validate correctly, but the latter signature results in a: > > header.d=acsac.org;dkim=fail (signature syntax error) > > Removing the ed25519 seems to help; Also, no indicators on the > dashboard > for the IPs, all in good standing, and can also deliver flawlessly > to all other ESPs. > > Are there similar experiences of reduced deliverability by senders > multi-signing, and including ed25519? > > With best regards, > Tobias > > -- > Univ.Prof. Dr.-Ing. Tobias Fiebig > T +31 616 80 98 99 > M [email protected] > _______________________________________________ > mailop mailing list > [email protected] > https://list.mailop.org/listinfo/mailop _______________________________________________ mailop mailing list [email protected] https://list.mailop.org/listinfo/mailop
