Email Routing Error 451

I am moving to a different IP block, and want to use email routing beta for incoming email in order to obscure IPs behind Cloudflare. I’ve decided the best way to do this is to use a direct IP, instead of dns or mx records that could be associated with our current dns names before the move.

When using “[email protected][]” for email address, I am able to add and verify the email address, but after that Cloudflare rejects incoming emails with “451 4.3.0 No available upstream.”.

While this is an unusual solution, it is a part of the RFC-5322 : 3.4.1. Addr-Spec Specification.

In case it needs to be said, I can email my forwarded email address at the server directly without error. The error is only when routed through Cloudflare, and Cloudflare successfully sends an email for verification.

Do you mean email address? If so, then it is “[email protected][IP address]”, with brackets included as per the specification.

This is likely a problem with a specific part of Cloudflare Email Routing not validating or handling it as a conforming email address.

You mean

[email protected] which forwards mails to [email protected] ?

Cloudflare has added a Email Routing feature, which is in beta. It forwards (bounces) email from [email protected] to [email protected] or whatever you would like. I am having it forward directly to my email server at its IP address like [email protected][]. This is a valid address, and works through Cloudflare’s email verification. It however does not work for forwarding email. I am trying to get Cloudflare developers to verify that this is an issue with the beta and fix it.

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