OK, so sending an email to my Yahoo address from Thunderbird, using my Comcast account and a spoofed "from" header matching my alias domain, works just fine. Sending from Gmail to Yahoo with the same "from" field is rejected. I guess that narrows it down some. It also makes my head hurt.
On Thu, Aug 21, 2025 at 8:28 AM Russell Clemings <rclemi...@gmail.com> wrote: > > > On Thu, Aug 21, 2025 at 8:10 AM Marcel Becker via mailop < > mailop@mailop.org> wrote: > >> >> On Thu, Aug 21, 2025 at 7:06 AM Russell Clemings via mailop < >> mailop@mailop.org> wrote: >> >>> 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 xxxx.xxx with ip >>> 209.85.214.178 = FAILURE. See >>> https://senders.yahooinc.com/smtp-error-codes/#authentication-failures >>> for more information. >>> >> >> >>> It looks to me as if Yahoo is expecting the "from" field to pass SPF >>> instead of (or in addition to) the envelope sender. Or is there a different >>> issue that I'm not seeing? >>> >>> >> You could follow the link in the SMTP message... >> > > I did. > > >> >> It seems your users are sending emails via their Google consumer accounts >> with domains in the "from" field, which are not properly set up to send via >> Google's servers. >> >> > Interesting point. I know you used to be able to spoof a "from" address > when sending from Gmail even if it was just an alias. Now you have to have > an actual mailbox at the alias domain. I'll try to do a test later today > with a spoofed "from" field using a different account and see if the > results change. > > > >> We require SPF or DKIM and we require either SPF or DKIM to align. >> >> Solution is to sign with an aligned DKIM domain. >> > > I'm not sure how to do that with a spoofed "from." > > >> >> -- Marcel >> >> >> _______________________________________________ >> mailop mailing list >> mailop@mailop.org >> https://list.mailop.org/listinfo/mailop >> > > > -- > =============================================== > Russell Clemings > <rclemi...@gmail.com> > =============================================== > -- =============================================== Russell Clemings <rclemi...@gmail.com> ===============================================
_______________________________________________ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
