Mailbox FULL in Outlook app

Situation: if your mailbox is full assuming that you are a Microsoft 365 user.

Task: Need to back up your email history properly and delete the old ones in your current mailbox.

Action:

Backup your old emails by folders

1. Open Outlook app, go to File> Open & Export> Import/Export
2. In Import and Export Wizard, Click on Export to a file> Outlook Data File (.pst)
3. In Export Outlook Data File, select each folder to backup one by one.

Saving backup in the cloud

1. After exporting the file into .pst, upload the physical file to SharePoint or contact IT.
2. Also, keep a copy of the file in your desktop folder so you can access the old email once needed.

Delete old emails

1. After the backup is completed, go to Outlook Web: https://outlook.office.com/mail/
2. Go to Settings by clicking the gear icon on the top right
3. General> Storage, in the Manage Storage tab, delete emails in the folders by selecting 12 months and older. Make sure the deleted emails in the folders are the ones you had backup before.

Accessing old emails from backup PST file

1. Open Outlook app and File> Open & Export> Open Outlook Data File
2. Upload the backup PST file here
3. The new backup email will be showing as an account in the left sidebar