Use case: Use this procedure to enable auto-expanding archiving for a user. Auto-expanding archiving lets Exchange Online add storage to the archive mailbox automatically as it fills, raising the limit from 100 GB to a maximum of 1.5 TB.
To enable auto-expanding archiving, do the following:
- Open User properties, select the Mailbox tab, and click Mailbox Archive.
- Select Enable auto-expanding archiving.
- Read the confirmation and click Enable.
- Click OK twice to apply the settings.
Important Notes:
Auto-expanding archiving cannot be disabled once enabled.
The mailbox must already have Enable archive selected, and the user must hold a license that includes Exchange Online Archiving.
Expansion does not begin until the archive reaches approximately 90 GB and can take up to 30 days to complete, during which the user may keep receiving archive quota warnings.
Removing the license later, for example when converting the mailbox to a shared mailbox during offboarding, limits the mailbox to 50 GB and stops archive expansion.
A mailbox with auto-expanding archiving enabled cannot be recovered if it later becomes inactive, and its archive cannot be moved back to on-premises Exchange.
