How To Fix “550 5.7.1 Unauthenticated email is not accepted from this domain” when forwarding facebookmail.com to G.Apps. We have two email domains: @uwo.ca which is hosted by us and @alumni.uwo.ca which is hosted by Google Apps. When Facebook sent a notification email to someone @uwo.ca who was forwarding their mail to @alumni.uwo.ca, we were …
https://support.google.com/a/forum/AAAA034zvV8kvUSIncA0ss/?hl=en

