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Incoming mail being block by my configserver setup.

Posted: 21 Jan 2020, 13:42
by JasGot
I have an account that can't receive mail from a vendor that uses Outlook 365.

I have been sent the NDR from the outgoing smtp server and the IT at the other end says I need to allow connection from the APAC region datacenter for O365.

I am trying to figure out how to change my filtering and protections to allow an entire "region" to be able to connect to my server without opening up to too many issues.

Years ago I added several CC codes to my CC deny list to stop spam and login attempts and it worked really well. But now I think I need to relax those rules or find a different method.

Here is my CC Deny list:

Microsoft says I need to allow connections from the APAC O365 region, but they don't say what countries.

Here is the NDR I was given,

1/10/2020 1:02:11 PM - Server at (??.227.211.??) returned '450 4.4.316 Connection refused [Message=Socket error code 10061] [] [LastAttemptedIP=??.227.211.??:25] [](Socket error code 10061)'

Any advise I can try would be greatly appreciated.