Deleting and Removing Healthmailbox* from OnPremise AD?

Hi @AzureTeam EnterpriseArchitecture ,

1.Can I delete and remove all 200+ HealthMailbox* objects from the OnPremise AD DS?

Yes, you can.

2.Will this have any dangerous impacts on the Hybrid provisioning or operations?

No, these health mailboxes are used for the Managed Availability feature, it uses special type of mailboxes, called Monitoring Mailboxes or health mailboxes, to simulate end-user kinds of tests. You could delete them but they'll be recreated if the MS Exchange Health Manager service is restarted.

3.Why there are some objects that are disabled and some of them are still active?

The life cycle of monitoring mailboxes is taken care entirely by Managed Availability components. No intervention is required.

For more details, you could read this topic: Exchange 2013/2016 Monitoring Mailboxes - Microsoft Community Hub

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