Issue between Microsoft and cloudflare nameserver causes spam emails?


We have a domain which is handled by Cloudflare. When an email is sent to a Microsoft email client (outlook, hotmail, etc.) and contains either or in its content, the email is tagged as spam automatically.

Here’s the error we generally get: Message was deferred due to Suspicious (Nameserver for

I doubt it has anything to do with Cloudflare, but I wondered if anyone had ever raised a similar issue.

Thank you

I don’t recall a similar question here nor do I see similar issues reported. That feels like an overly aggressive spam filter, any M$ setting that can side-step this? But, if it continues to deal issues can you loop in Support?

If necessary, to contact Cloudflare Customer Support, login & go to and select get more help.

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