More SPF/DKIM fun. Just got: ----- The following addresses had permanent fatal errors —— <REDACTED@xxxxxxxx> (reason: 450 4.7.26 Service does not accept messages sent over IPv6 [2001:638:708:30c9::12] unless they pass either SPF or DKIM validation (message not signed)) Whiskey Tango Foxtrot. So they give their mail server an IPv6 address but then don’t accept certain messages on that that they would happily accept over IPv4. Grüße, Carsten