Email routing returns unclear 521 5.3.0 Upstream error

When I send a test email to my Email Routing address, it bounces with a 521 5.3.0 Upstream error. with no further information aside from a code after the message which I will share with Cloudflare employees if asked.

Nevermind, I’ve finally tracked it down to a misconfiguration on my local mail server. That said, I believe it would be helpful to forward on the upstream error message instead of discarding it at this level, though I suppose there could be privacy implications to that.

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