Office 365: Enable Auto-Expanding Online Archives

To determine whether auto-expanding archive is enabled, you have to check using Exchange Online PowerShell.

Alternatively, by going through the Microsoft 365 Exchange admin center → Mailboxes → click on the affected user → Others → Manage mailbox archive → If the mailbox quota displayed is over 100 GB, then auto-expanding archive is enabled. But if it 100 GB, then auto-expanding is not enabled.

Auto-expanding archive can only be enabled using PowerShell.

• Open PowerShell as Administrator and run the cmdlets below:
• Set-ExecutionPolicy Unrestricted 
• [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12 
• Install-Module ExchangeOnlineManagement 
• Import-Module ExchangeOnlineManagement 
• Connect-ExchangeOnline (type your admin credential when prompted)
• Enable-Mailbox user@domain.com -AutoExpandingArchive

To check if it has successfully been enabled, run the cmdlet below:

Get-Mailbox "user@domain.com" | FL Archive*Quota,AutoExpandingArchiveEnabled

Then confirm AutoExpandingArchiveEnabled is set to True