Cloudflare DNS PTR Record Issue with Specific Email Providers

we have a problem that after activating Cloudflare, some of our emails are not sent to certain email providers like freenet.de we recieve the folloing log:

[email protected]: host emig.freenet.de[195.4.92.216] said: 550-Inconsistent/Missing DNS PTR record (RFC 1912 2.1) (k76a17.meinserver.io) 550 [148.251.209.167]:51009 (in reply to RCPT TO command)

Our dns config on Cloudflare

We tried troubleshooting the email settings related to Cloudflare and made some changes, but it didn’t resolve our issue. Any help and suggestions would be appreciated.

The target of your MX record (mail.) is :orange:, and it should be :grey:. Changing that on its own might be enough to convince Freenet that the mail is legitimate. You could also ask your IP address provider (Hetzner) to change their PTR for 167.209.251.148.in-addr.arpa from hulle24.de to mail.hulle24.de, in which case the IP address you are sending from will fully match both forward and reverse DNS.

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Thanks for your answer Michael. Our A mail record pointing to the IP was on DNS only (and not proxied) before today and it did not work with this setting either. I will also try to contact our hosting and ask them to change our PTR to the value mail.hulle24.de and and test it again with the A mail record on DNS only. Any further suggestions and changes are very apricated.

Your mail server is identifying itself in its banner and HELO as k76a17.meinserver.io. You may want to change that to mail.hulle24.de if that’s going to be your reverse DNS entry.

(This would typically be done in the Postfix myhostname setting, but I can’t speak to your server configuration.)

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