Forum Discussion
Exchange System Mailboxes after migration to Exchange 365
Hi LeonPavesic
Thanks for your reply.
Do you know why other system mailboxes/arbitration mailboxes are not count as mailboxes? And why are these mailboxes counted as mailboxes, despite they are system mailboxes?
When we don't host mailboxes on-premise, we don't need a license (because it is only a hybrid server). With this 2 mailboxes we do need a license?
Our Exchange 2019 server is only used as relay-server, so our applications can send mail to our users in Exchange 365. So, I think the extest-mailbox is not needed anymore.
Why do we use the DiscoverySearch-mailbox? There are no mailboxes with messages to search for.
Kind regards,
Arjan
Hi ArjanBroekhuizen,
thanks for your update.
The “extest” and “DiscoverySearchMailbox” are indeed system mailboxes, but they serve specific purposes and are treated differently from other system or arbitration mailboxes.
Regarding licensing, typically, you don’t need a separate license for system mailboxes.
If your Exchange 2019 server is only used as a relay server, and you’ve migrated all user mailboxes to Exchange Online, you might not need the “extest” mailbox anymore and you can remove it.
The “DiscoverySearchMailbox” is used for In-Place eDiscovery, which is a tool for searching mailboxes in your organization. Even if there are no user mailboxes on-premises, there might be scenarios where the “DiscoverySearchMailbox” is still needed.
If you’re certain that there’s no need for eDiscovery in your on-premises environment, you could also consider removing this mailbox.
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Kindest regards,
Leon Pavesic
(LinkedIn)