On 5/7/26 09:55, Stephen J. Turnbull wrote:
Stephen Daniel writes
550 5.7.9 This mail has been blocked because the sender is unauthenticated. Yahoo requires all senders to authenticate with either SPF or DKIM. Authentication results: DKIM = FAILURE - SPF XXX.org with ip X.Y.Z.W = SUCCESS.
That is quite weird -- it says SPF authentication *succeeded*, which should be sufficient. It's possible it's a Yahoo misconfiguration which will fix itself, as far as SPF is concerned. But you should still find out what's going on with DKIM.
I think this may be Yahoo policy in that SPF passed but wasn't aligned with the From: domain, thus DMARC failed. It appears that Yahoo, and in some cases Gmail reject mails which fail DMARC even if the From: domain publishes no DMARC policy or DMARC policy = none.
The only way around this in current Mailman is to apply DMARC mitigations unconditionally.
-- Mark Sapiro <mark@msapiro.net> The highway is for gamblers, San Francisco Bay Area, California better use your sense - B. Dylan