Problem sending emails

Hey guys

We are using a combination of Cloudflare for DNS, Zoho for email management and Sendgrid for sending emails via API.

In the Sendgrid console we can see that we are experiencing instability when sending emails, where we constantly receive the following message: “421 4.3.0 Upstream error, please check Postmaster · Cloudflare Email Routing docs for possible reasons why.”

Consulting the documentation provided, we did not find any troubleshooting regarding the possible causes. Please note, we have not made any recent changes to the settings.

I would like help finding a cause for the problem.

Welcome to the Cloudflare Community. :logodrop:

I didn’t see any mention of Cloudflare Email Routing in your setup, nor any reason why you should be using it, yet your error is clearly from Cloudflare Email Routing. Can you indicate if you are using Cloudflare Email Routing and explain why?

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