Troubleshooting - Mail Client Connectivity and Mail Flow

[OasisTech2020]

We have an On-Premise Exchange Server 2013.  Over the last few days, the mail clients aren't connected to the Exchange database and mail flow has stopped.  

[PS] C:\Windows\system32>Test-mailflow
RunspaceId         : ecfa2d61-ec65-41ae-bc63-2c1d6261b153
TestMailflowResult : *FAILURE*
MessageLatencyTime : 00:00:00
IsRemoteTest       : False
Identity           :
IsValid            : True
ObjectState        : New

Also, Delivery Reports are throwing the following errors:

Server xxxxx.domain.com in domain domain.com encountered an unexpected error. Diagnostic information for this error: The message-tracking data on server xxxxx.domain.com had invalid data in column 12 for this message. Event "THROTTLE" will be ignored.

Any suggestions on how to diagnose/repair this situation?

Thanks.

[#2]

Hi,

I'm Kishore from Microsoft Exchange On-premises team.

Seems like the issue arised - Dec 2019.

could you please help me collect few details on this issue.

1. Before this issue shows up - were there any changes made in your environment.
2. I believe the issue might have been fixed - if yes, could you share what changes you have made to fix this.
3. Following the change to fix this were there any additional issues arised?

Kind regards,
KishoreV