Gmail rejecting forwarded email from Cloudflare Email Routing with 550 5.7.1 permanent error

Hello,

I’m using a Gmail account to receive emails forwarded from my domain via Cloudflare Email Routing. Recently, some messages are failing to deliver with this bounce message:

upstream (gmail-smtp-in.l.google.com.) error: Unknown error: permanent error (550): 5.7.1 [IP] Gmail has detected that this message is likely unsolicited mail. To reduce the amount of spam sent to Gmail, this message has been blocked.


SPF: pass

DKIM: pass

DMARC: none

Cloudflare Activity Logs show DMARC: none

These messages were previously delivered successfully. Even being blocked within an existing thread.

I’d like to understand:

Why Gmail is now rejecting messages forwarded via Cloudflare Email Routing.

If there’s anything I can do to stop Gmail marking these forwarded messages as spam, without switching away from Cloudflare.

Thank you for any help
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