Email Routing stopped working

We have 3 email addresses @mooglyblog.com that route to gmail addresses. The catch all account is setup as well. All has been working well for almost a year until this morning when people are getting errors sending email to our routed addresses. The error is:

|521 5.3.0 Upstream error, please check https://developers.cloudflare.com/email-routing/postmaster for possible reasons why. TPwm37vvyLQC|