Overview
In Druva inSync, Microsoft 365 Shared Mailboxes (SMBs) are backed up using an SMB License, which is different from a standard Active License. However, depending on the mailbox configuration, backup settings, and profile associations, a Shared Mailbox may temporarily or permanently consume both license types.
This article explains the scenarios under which license types are consumed or released.
1. When Does a Shared Mailbox Consume Both Active and SMB License?
A Shared Mailbox (SMB) consumes both an Active License and an SMB License when:
The user’s profile has other User Apps enabled, like OneDrive (OD)/ Endpoint.
inSync backs up both Exchange Online (Shared mailbox) and OneDrive under that profile, triggering Active License consumption due to OneDrive and SMB license due to Shared mailbox.
📌 Example: A mailbox was converted to SMB, but the associated profile still includes OneDrive, and the user is active in Microsoft 365. inSync treats this as an active user with Exchange and OneDrive workloads.
2. When Does a Shared Mailbox Consume Only an SMB License?
A Shared Mailbox will only consume an SMB License when:
The User associated with the mailbox does not have any other User app (like OneDrive or Endpoint) apart from the Shared Mailbox in Microsoft 365.
The associated user is inactive (not licensed for M365) or soft-deleted. This will cause the user to consume the Preserve license due to OneDrive and SMB will continue to be consumed due to the Shared mailbox.
The inSync profile only has Exchange Online enabled, and OneDrive is disabled.
OneDrive was never discovered or backed up previously.
3. When will the M365-Deleted Shared mailbox free up the SMB License in Druva?
An SMB license is automatically released by Druva when:
When a Shared Mailbox is permanently deleted from Microsoft 365, the shared/resource mailboxes will consume the M365 preserve license in inSync and free up the Shared/Resource license.
If the Shared mailbox is in soft soft-deleted state, the backups may still continue to take place until and unless the mailbox gets deleted permanently after the retention period expires.
You may choose to retrieve soft soft-deleted mailbox using the command below:
Get-Mailbox -SoftDeletedMailbox | Select-Object Name,ExchangeGuidUndo-SoftDeletedMailbox -SoftDeletedObject USERNAME
Mailboxes can be recovered within 30 days of being deleted.
For more information, please refer to Undo-SoftDeletedMailbox
When the Shared mailbox is deleted from Druva, the SMB license will be freed up.
4. What Happens if an SMB is Converted Back to a User Mailbox in M365?
When a Shared Mailbox is converted back to a regular user mailbox in Microsoft 365:
It will not automatically revert to a User Mailbox even if it is converted back to a User Mailbox in Microsoft 365 Exchange Online. This change must be managed manually within inSync.
Conversion of a shared mailbox back to a user mailbox will require changes to be made in the backend with the help of Druva support.
5. What if the Profile has both EXO and OD enabled, but OD Was Never Backed Up? Will the SMB Stay SMB or Consume an Active License?
If the Shared mailbox (EXO) is actively being backed up, but OneDrive (OD) has never been discovered or backed up, then:
The mailbox will continue to consume only the SMB License.
However, if OD is discovered or a backup is attempted, then an Active License will be consumed in addition to the SMB License.
Summary Table
Scenario | License Consumed in Druva |
Shared mailbox with only EXO workload enabled in profile | SMB License only |
Shared mailbox with EXO + OD workload (OD backed up) | SMB + Active/Preserved License |
Shared mailbox converted back to a user mailbox in Microsoft 365 | Continue to consume SMB license (Need to involve Support to change SMB to user mailbox) |
Shared mailbox deleted from Microsoft 365 | SMB License freed |
EXO and OD are enabled, but OD never backed up | SMB License only (unless OD backup is triggered) |
Should you encounter a scenario not described above, please reach out to support for assistance.