About 6 weeks ago, email from my domain to email aliases within my domain stop working, and I cannot figure out what might have changed to cause this.
Our domain sends email via mailgun, but the mailgun configuration has not been changed in over a year (and everything was working until a few weeks ago). And only one specific godaddy path is not working:
Email from our domain to any outside email address works.
Email from our domain to an actual mailbox in our domain works.
Email from outside our domain to an actual mailbox in our domain works.
Email from outside our domain to an email forwarder in our domain works.
Email from inside our domain to an email forwarder in our domain *no longer works*.
So to be clear: if from my account firstname.lastname@example.org I send to email@example.com, and I have that address with forwarders to firstname.lastname@example.org and email@example.com, both recipients get the email. If I send that same email from firstname.lastname@example.org, no one gets the email.
Mailgun reports that the email was accepted by godaddy with status 250 in all cases, so it is the godaddy forwarding that somehow won't forward correctly (any longer) when the sender is my domain.