Purge Emails in Outlook / Archive Mailbox Almost Full
In Outlook 365, older emails that are not deleted and purged automatically get retained, according to our email retention policy, and stored in an online archive.
To make room in your archive mailbox, delete any items you don't need, including Junk Mail or older messages, and empty your Deleted Items folder.
Permanently erase messages from Outlook
Once you have deleted an email, it moves to a Recoverable items store. To permanently erase all of your Deleted Items (https://go.microsoft.com...