Forum Discussion
Exchange System Mailboxes after migration to Exchange 365
Hello all,
After the migration off the mailboxes to Exchange 365, there are 2 mailboxes in our on-premise environment: extest + DiscoverySearchMailbox.
Because of this 2 mailboxes, the Exchange server has the 'Mailbox Server'-role. I think this is not neccesarry. I don't understand why this 2 mailboxes are counted as normal mailbox, because other system mailboxes aren't and also not visible.
Does anyone know what the function is off this mailboxes?
Kind regards,
Arjan
10 Replies
ArjanBroekhuizen Hello, Arjan, I have read the recommendations from other users and have several insights to add. Before removing "extest," make sure it's not used for any specific tests. If it's not necessary, removing it can tidy up your on-premises setup.
Another recommendation - since your Exchange server is only a relay and has no user mailboxes, you might not need the "DiscoverySearchMailbox" if there's no eDiscovery requirement. Consider removing it for a cleaner setup. Check if your on-premises Exchange server serves any other purpose besides email relaying. If not, retiring it could simplify things and lower maintenance.
- Hi @BarryBoblon,
I'm sure that our server is only used as relay server. Besides the system mailboxes, the DiscoverySearcMailbox is the only mailbox on this server (extest is removed already).
When I remove the Discovery-mailbox, is there a possibility to re-create it if necessary?
Kind regards,
ArjanYes, it is possible to recreate the DiscoverySearchMailbox if necessary. The DiscoverySearchMailbox is a system mailbox in on-premises Exchange used for In-Place eDiscovery. If you remove it and later find the need to perform eDiscovery searches or if it's required for compliance reasons, you can recreate the DiscoverySearchMailbox.
To recreate the DiscoverySearchMailbox, you can use the New-MailboxSearch cmdlet in the Exchange Management Shell. Here's an example of the command:
New-MailboxSearch -Name "Discovery Search Mailbox" -InPlaceHoldEnabled $true -SourceMailboxes "email address removed for privacy reasons", "email address removed for privacy reasons" -StartDate "MM/DD/YYYY" -EndDate "MM/DD/YYYY"
Replace "email address removed for privacy reasons", "email address removed for privacy reasons" with the mailboxes you want to include in the search. Set the appropriate StartDate and EndDate for your search criteria.
Keep in mind that removing the DiscoverySearchMailbox means you'll lose any existing In-Place eDiscovery searches associated with it. Recreating it will start with a new mailbox and new searches.
Always ensure that you understand your organization's compliance and eDiscovery requirements before making such changes. If in doubt, consult with your IT or compliance team.
Hi ArjanBroekhuizen,
The "extest" and "DiscoverySearchMailbox" mailboxes are system mailboxes in on-prem Exchange, and they serve specific purposes:extest Mailbox: The "extest" mailbox is created for testing purposes within on-premises Exchange environments. It is not a standard user mailbox but is used for various testing scenarios, like database and connectivity tests. After migrating to Exchange Online, this mailbox typically serves no further purpose. You can consider removing or disabling it to clean up your on-premises environment. However, make sure that it's no longer needed for any specific tests before doing so.
DiscoverySearchMailbox: The "DiscoverySearchMailbox" plays a crucial role in on-premises Exchange for In-Place eDiscovery. It is a dedicated mailbox used for conducting searches and discovering content within Exchange mailboxes, which is essential for compliance and legal requirements. Even after migrating user mailboxes to Exchange Online in a hybrid or coexistence setup, retaining the "DiscoverySearchMailbox" is advisable. Removing it can disrupt eDiscovery and compliance features.
As for the "Mailbox Server" role on your on-premises Exchange server, it is typical for it to continue hosting certain mailbox roles and system mailboxes, even after user mailbox migration to Exchange Online.
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Kindest regards,
Leon Pavesic
(LinkedIn)- Hello
We have an On-Prem exchange server 2013 in hybrid mode - 99% of the mail boxes have been moved to Office 365- Can we move the discovery mailbox to office 365 and convert it as a shared mailbox? We would like decommission the exchange server and use AD sync for password synchronization.
Thanks- Hi Krish70,
Why would you move the discovery mailbox tot Office 365? This is a system mailbox and Office 365 will have it's own discovery mailboxes.
Kind regards,
Arjan
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.Please click Mark as Best Response & Like if my post helped you to solve your issue.
This will help others to find the correct solution easily. It also closes the item.If the post was useful in other ways, please consider giving it Like.
Kindest regards,
Leon Pavesic
(LinkedIn)
