DNS Records, PTR, and Switching to M365 Email

Website, Application, Performance DNS & Network
1

What is the name of the domain?

stmonicastl.org

What is the error number?

550 5.7.364 and 550 5.7.1

What is the error message?

550 5.7.364 Remote server returned invalid or missing PTR (reverse DNS) record for sending domain → 550 5.7.1 Connections not accepted from servers without a valid sender domain.flph824 Fix reverse DNS for 40.107.95.110

What is the issue you’re encountering

Not being able to send emails to certain domains because reverse DNS is detecting different domains

What steps have you taken to resolve the issue?

Called Microsoft, my registrar, ISP, and now trying this forum to figure out PTR Record.

What feature, service or problem is this related to?

DNS records

Screenshot of the error

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1 Like
2

I have just run into the same issue with a client. I am still looking myself, but if I find anything I will post here.

3

We fixed it by pointing our A records to the proper registrar and adding a PTR record by doing a name resolution on the Microsoft DNS.

1 Like
4

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