Did You Know that Microsoft 365 Groups Come with a Hidden 50 GB Mailbox?

In the bustling ecosystem of Microsoft 365, where Teams chats fly and SharePoint files pile up, there's a sneaky feature that often flies under the radar which is Microsoft 365 group mailbox. Every Microsoft 365 Group automatically gets its own dedicated group mailbox. It's packing a full-fledged email inbox with a generous 50 GB storage and no extra licenses needed.

This group mailbox acts as the central nervous system for your team's communications. Emails sent to the group's address (like [email protected]) land here, accessible to all members via Outlook or the web.

How to access Group Mailboxes?

When you click the “Group Icon” in Microsoft Outlook, you can see the groups which you’re included.

If you are a Group Owner, when you click the setting icon in the group mailbox, you will see the mailbox storage.

What happens if the Group Mailbox filled?

Unfortunately, a group mailbox cannot be expanded even with additional license. All you have to do is clear the Group Mailbox.

Common errors showing to users

When the Group Mailbox storage filled, users who are sending emails to the group will get NDR mentioning mailbox capacity.

"550 5.2.2: The email account that you tried to reach is over its quota."

"The recipient's mailbox is full and can't accept messages now. Please try resending your message later, or contact the recipient directly."

How To Clear Group mailboxes?

From settings, go to manage mailbox. Then empty Inbox or Sent Items.

Also you can delete selected range emails.

Does deleting emails from O365 Group affect any of members Mailbox?

No. Deleting emails from Group Mailbox won’t effect the emails in members’ mailboxes.

First check the Group setting of “send copies to group conversations to group members” enabled. Otherwise, members in the will not receive emails to

Can we get Group Mailbox Backup?

Yes. From Microsoft Purview Content Search you can get the Mailbox Backup in pst form. (Same procedure as Mailbox Content Search)

What is the Best method to manage Group mailboxes?

Set Up Retention Policies: Automate the Future Head to the Microsoft Purview compliance portal > Data lifecycle management > Retention policies. Create a policy for Microsoft 365 Groups.

• Retain for 90-365 days, then auto-delete.

• Apply to all groups or specific ones.

How Group Mailboxes Differ from Shared Mailboxes?

Group mailboxes often get compared to shared mailboxes, another popular Microsoft 365 option for team email. While both enable multi-user access, they serve different needs. Shared mailboxes are simpler for basic email delegation, but group mailboxes shine in collaborative scenarios.

Powershell commands to monitor Group Mailboxes.

• Get-Mailbox -GroupMailbox <groupname> |ft ProhibitSendReceiveQuota,ProhibitSendQuota,IssueWarningQuota

• Get-MailboxStatistics <groupname> | ft TotalDeletedItemSize,TotalItemSize.