In Outlook, if you have multiple accounts, maybe thousands of Outlook items will occupy the space. In this case, you can set to move the older items to release the Outlook space by using AutoArchive.
Move outlook items older than n days/weeks/months
1. Enable Outlook, click File > Options, in the Outlook Options dialog, click Advanced in left pane, then click AutoArchive Settings in right section.
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2. In the AutoArchive dialog, check Run AutoArchive every 14 days checkbox, you can change 14 to other numbers as you need. Then go to Clean out items older than drop down list, choose Months, Weeks or Days as you need, and type the number in the box.
3. Click OK > OK to close dialogs.
If you just want to move items in one folder, you can right click at the folder, select Properties from the context menu.
In the Properties dialog, under AutoArchive tab, check Archive this folder using these settings, then you can change the number and criteria in Clean out items older than section.
