One customer - cannot receive mails from Exchange Online - Insists on IPv4 - how to handle

Question

Hi,

i have an incident that i cannot handle atm.
Recently a customer does not receive mails - the errors are below. I have sent the logs with my Gmail Account to them (which works). The insist on an IPv4 address to analyze or handle the mail (?)

4/8/2021 4:31:07 PM - Server at ***********.COM returned '550 5.4.316 Message expired, connection refused(Socket error code 10061)'
4/8/2021 4:21:04 PM - Server at domain.ro returned '450 4.4.316 Connection refused [Message=Socket error code 10061] [LastAttemptedServerName=domain.ro] [LastAttemptedIP=*******:25] VI1EUR04FT012.server.domain.protection.outlook.com'

As i cannot create a transport rule that says - use this "old mail server". How can i deal with it?
I have a workaround in mind that relies on our hybrid Exchange - but i want to get rid of that and not use it for any service then user management.

Anyone has a hint?

BR
Stephan

Answer 1

Hi @StephanG ,

I removed the personal information.
Do you mean this recipient could receive emails from an Gmail account but not the O365 accounts?

For the error: 450 4.4.316, it maybe because of the firewall. Please check this:Error code: 450 4.4.316 Connection refused

Also an article points that it could also be rounting errors:http://ezoltan.blogspot.com/2019/07/550-54316-message-expired-connection.html
Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

Regards,
Lou

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