Dealing with Office 365 Mailbox Size Warning

Himanshu Goyal    Himanshu Goyal     Updated On - 29 Mar 2019

Last week, some of my Office 365 users received a warning “Mailbox size limit exceeded.” If you’ve also got this warning, then don’t worry about it. This warning is just to inform users that the Office 365 mailbox size has reached the defined limit of sending and receiving messages.

However, getting rid of this warning is crucial if you want your users to use their Office 365 account continuously. To remove this warning from user’s account, you’ll have to set mailbox limit in your Office 365 account. So, to help you with this problem, we have mentioned some methods to set Exchange mailbox size limit.

Methods to Set Exchange Mailbox Limit

The only manual method to set the Office 365 mailbox size limit for users is to use Exchange Management Shell. However, it’s up to you whether you want to set a mailbox size limit for a single user or multiple users.

Setting Mailbox Size Limit for a Single User

  1. Connect to Exchange Online using Remote PowerShell.
  2. After connecting to Exchange Online, run the below command to set the mailbox size limit for a single user.
  3. Set-Mailbox < UserID > -ProhibitSendQuota < Value > -ProhibitSendReceiveQuota < Value > -IssueWarningQuota

    Note: In this command, the User ID represents the UPN, email address, or GUID or a single user. The Value parameter represents a number in MB, KB, or GB. See the below example to set the mailbox limit to 30 GB for single user.

    Set-Mailbox TestUser@testdomain.com -ProhibitSendQuota 29GB -ProhibitSendReceiveQuota 30GB -IssueWarningQuota 28GB
  4. Now, check whether the current list of quotas is attached to the mailbox or not. You can use the below command to achieve this:
  5. Get-Mailbox < User ID > | Select *quota

Using this technique, you can easily set the Office 365 mailbox size limit for a single user.

Setting Mailbox Size Limit for Multiple Users

Setting mailbox size limit for multiple users is almost similar to a single user. However, there is a little difference in the PowerShell command that is used to set the mailbox size limit.

  1. Connect to Exchange Online using remote PowerShell.
  2. Once connected, run the below PowerShell command to set the mailbox size limit.
  3. Get-Mailbox | Set-Mailbox -ProhibitSendQuota < Value > -ProhibitSendReceiveQuota < Value > -IssueWarningQuota < Value >

    You can apply filters to the Get-Mailbox cmdlet or to Get-User cmdlet to control the users for whom you’re applying these changes. Below is an example with three cmdlets are used to filter the command to the sales department of an organization.

    Get-User | where {$_.Department -eq “Sales”} | Get-Mailbox | Set-Mailbox -ProhibitSendQuota < Value > -ProhibitSendReceiveQuota < Value > -IssueWarningQuota < Value >

Using the above command, you can easily set the mailbox size limit for multiple users. After setting the mailbox size limit, you’ll not receive the ‘mailbox size limit exceeded’ warning. However, if you still see the same warning, then it means your Office 365 subscription storage quota is full. So, you’ll have to empty the mailboxes or other folders.

In such cases, deleting the Office 365 mailbox data is not an option as it contains crucial information of a user or organization. The only ideal option is to backup Office 365 mailboxes with a useful tool.

Kernel Office 365 Backup Tool

The manual methods to back up Office 365 mailboxes are not reliable because there are risks of data corruption or data loss. But, with Kernel Office 365 Backup tool, you don’t have to worry about the security of your data. It is among the best utilities to export Office 365 mailboxes to PST that enable users to backup even permanently deleted items in the PST format.

Using this software, you can quickly backup your Office 365 mailboxes and free-up storage in the Office 365 account to get rid of the “mailbox size limit” warning.

Conclusion

When Office 365 users get any warning like Mailbox Size Limit Exceeded, then resolving this issue is a necessity. In this article, we have mentioned some useful techniques to eliminate this warning. Also, we have referred a third-party tool that can be helpful to back up your mailbox data before freeing up some space from the mailboxes.