The original message was received at Fri, 24 Mar 2023 09:36:17 -0700 from Athenae [192.168.3.12] ----- The following addresses had permanent fatal errors ----- (reason: 550-5.7.26 The MAIL FROM domain [cygwin.com] has an SPF record with a hard fail) ----- Transcript of session follows ----- ... while talking to gmail-smtp-in.l.google.com.: >>> DATA <<< 550-5.7.26 The MAIL FROM domain [cygwin.com] has an SPF record with a hard fail <<< 550-5.7.26 policy (-all) but it fails to pass SPF checks with the ip: <<< 550-5.7.26 [173.164.175.65]. To best protect our users from spam and phishing, <<< 550-5.7.26 the message has been blocked. Please visit <<< 550-5.7.26 https://support.google.com/mail/answer/81126#authentication for more <<< 550 5.7.26 information. k1-20020a170902c40100b0019acbf1dc4asi32141273plk.181 - gsmtp 454 4.0.0 Service unavailable