This sounds like you’re connecting to the wrong MX for the domain you’re attempting to send to.
Have you verified that the domains are still in use? Have you checked that you can mail to them from different IPs? If you can mail to those on different IPs then I’d open a ticket with MS. Laura Sent from my iPhone > On Jul 31, 2020, at 8:37 AM, David Malagon via mailop <[email protected]> > wrote: > > > > Hello. > > We are experiencing a weird issue today. Never seen this, but some of our > customer ips are receiving the following error message from Microsoft: > > 4.7.1 Unable to Relay. ATTR37 > > Any clues? > > Someone at Microsoft maybe has an idea? > > Thanks a lot. > > Regards > > > > > > _______________________________________________ > mailop mailing list > [email protected] > https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop
_______________________________________________ mailop mailing list [email protected] https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop
