In most cases, the 1023 events are harmless. You needn't worry about it.
For more information, please refer to the articles below:
259578.KB.EN-US XADM: Event ID 11 Or 1023 Appear When Starting Exchange
188594.KB.EN-US XADM: Event ID 1023 Reports Logon Failure Audit
If there is anything else that I can do for you, don't hesitate to let me
know. Have a nice day.
Microsoft Online Support Professional
Get Secure! - www.microsoft.com/security
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