How to Manage User Mailbox Storage Quotas in Microsoft 365

Managing user mailbox storage quotas in Microsoft 365 involves adjusting the settings within the Microsoft 365 Admin Center or using PowerShell. Here’s how you can do it:

Using the Microsoft 365 Admin Center:

  1. Sign in to the Admin Center:

  2. Navigate to the Users:

    • In the left-hand navigation pane, select Users > Active Users.

  3. Select a User:

    • Click on the name of the user whose mailbox quota you want to manage.

  4. Go to Mail Settings:

    • Under the user’s details pane, click on the Mail tab.

  5. Adjust the Storage Quota:

    • In the Mailbox settings section, you can view and adjust the Mailbox storage quota settings.
    • Update the values as needed and save your changes.

Using PowerShell:

  1. Connect to Exchange Online:

    • Open PowerShell (Run as Administrator).
    • Install the Microsoft Exchange Online Management module if you haven’t already: 
      Install-Module -Name ExchangeOnlineManagement
    • Import the module and connect to Exchange Online: 
      Import-Module ExchangeOnlineManagement
Connect-ExchangeOnline -UserPrincipalName <admin_user>@<tenant_domain> -ShowProgress $true

  2. Set Mailbox Quotas:

    • To change the mailbox usage quota for a user, use the Set-Mailbox command. Replace <UserEmail>, <ProhibitSendQuota>, <ProhibitSendReceiveQuota>, and <IssueWarningQuota> with appropriate values. 
      Set-Mailbox -Identity <UserEmail> -ProhibitSendQuota <ProhibitSendValue> -ProhibitSendReceiveQuota <ProhibitSendReceiveValue> -IssueWarningQuota <IssueWarningValue>

      Example:

      Set-Mailbox -Identity user@example.com -ProhibitSendQuota 49.5GB -ProhibitSendReceiveQuota 50GB -IssueWarningQuota 45GB

  3. Verify the Changes:

    • To verify the changes, use the Get-Mailbox command: 
      Get-Mailbox -Identity <UserEmail> | Format-List ProhibitSendQuota,ProhibitSendReceiveQuota,IssueWarningQuota

Notes:

  • ProhibitSendQuota: When the mailbox reaches this quota, users can receive emails but cannot send.
  • ProhibitSendReceiveQuota: When the mailbox reaches this quota, users cannot send or receive emails.
  • IssueWarningQuota: When the mailbox reaches this quota, users receive a warning.

Important Considerations:

  • Default storage quotas are often adequate for most users, but some users may need adjustments based on their usage patterns.
  • Keep track of storage usage to avoid potential disruptions in communication.

By following these steps, you can effectively manage the storage quotas for your Microsoft 365 users.