Step 1: Search for Large Attachments in your Outlook Mailbox

• Open Outlook 2016 mail and click on the "File" tab in the top left corner.
• Click on "Cleanup Tools” (1) in screenshot below followed by clicking on "Mailbox Cleanup" (2) in screenshot below.
• Just below the mailbox cleanup you will see the current amount of space free in the maximum mail storage allocation of 49GB.
• You should have at least 15 GB or more free of the 49GB mailbox storage allocation.

Step 2: Delete Old or Large Emails

• In the "Mailbox Cleanup" dialog box, click on "Find older or larger items" to search for emails that are taking up a lot of space.
• Choose the criteria for the search, such as the age or size of the emails, and then click "OK". Recommend searching on anything greater than 1024KB
• Select the emails that you want to delete and then click "Delete" to remove them from your mailbox.

Step 3: Save and Remove Attachments

• Open the email with the large attachment that you want to remove.
• Right-click on the attachment and then select "Save All Attachments" to save the file to your computer.
• Once the attachment is saved, right-click on it again and select "Remove" to remove it from the email.
• Confirm the deletion by clicking "Yes".
• Resave your email if you want to keep the text of the mail itself. Otherwise you can delete the email itself as well.

Step 4: Also Search your inbox for folders that contain many “informational” type emails.

Step 5: Empty your deleted items folder

• When you are finished deleting all old mails, don’t forget to empty your deleted items folder by scrolling down the list of folders and finding Deleted Items in the list of folders
• Right Click on Deleted items and click on Empty Folder and then click Yes.

By following these steps, you can reduce the size of your mailbox in Outlook 2016 by searching for large attachments and removing them, and saving the mail.