Hi @Ian562 ,
The same as Andy said, you could run the following command to scope to recipients in email address policy. But according to the information you provided, I noted that you want to modify the Default Policy, we cannot change the type or attributes of recipients in the Default Email Address Policy (applicable to all recipient types).
Set-EmailAddressPolicy -Identity "<>" -RecipientContainer <> -RecipientFilter <>
What’s the version of your domain controller?
According to the research on the error message, I found a similar case in Windows server 2008 R2, please refer to: A paged LDAP query fails on the second page and the pages that follow in Windows Server 2008 R2
Please pay attention to the solution needs to modify the registry. If you modify the registry incorrectly, it will have a serious impact, so it is recommended that you back up in advance.
Please refer to: How to back up and restore the registry in Windows
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