Export existing older emails to backup file (pst). This process can be used for any type of account that you have in your Outlook; public folder (add it as a favorite first), shared mailbox or your account.
- Open Outlook>Click on the File tab>Click on Open & Export>Click on the Import/Export button
- Select Export to a file>Click the Next button
- Select Outlook Data File (.pst)>Click the Next button
- Navigate in the folder list to the location of the folder (you may need to scroll down)>Click the Filter... button
- Click the Advanced tab>Click the drop down next to Field and hover on Date\Time and select Received
- Click the drop down arrow next to the Condition field and select on or before>Enter the value desired in the format mm/dd/yyyy
- Click on the Add to List button>Click the OK button>Click on the Next button
- Click the Browse button to select a location to store the file and enter a name for the backup file>Click on the Finish button
Delete the emails exported in the previous step
- Open Outlook>Navigate to the applicable folder
- Change your view to arrange emails by Date only
- Click on View>Uncheck the box next to Show as Conversations in the Messages section of the ribbon
- Verify that Date is selected in the Arrangement section of the ribbon
- Select all of the emails that fit the date range of the emails that were exported
- Click the Delete key on your keyboard
- Click OK to the warnings that appear