An Outlook 2010 user wondered what Clean Up folder does:
What is "Clean Up Folder" and how does it compare to "Empty Folder"?
Empty Folder empties the folder (Deleted Items and Junk email), with the messages permanently deleted. You cannot easily recover them.
Clean up Folder moves all redundant messages in the current folder to the designated "Cleanup" folder. These messages aren't deleted, just moved. Redundant messages are early messages in email exchanges, which quote the previous message, which quotes the previous message… so in a long thread, you may end up with 6 or more copies of the early messages. After running Clean Up folder, the early messages are moved to the cleanup folder.
In some respects it's similar to archiving, but messages are moved by duplicated content, not by the last modified or received date. Using Cleanup to move mail to a "cleanup" pst file may better meet the needs of some users – the data file size is reduced but all mail is still in the main data file and easy to find.
The Clean up command is on the Home Ribbon. You can clean up only the selected conversation, all mail in the folder, or all mail within the selected folder and it's subfolders.
The first time you access it, the Clean up Folder dialog opens. Click the Settings button to configure options. (Clicking the Setting button opens the File, Options, Mail dialog.)
Configure Clean Up options in File, Options, Mail.
If no cleanup folder is selected, Outlook uses the Deleted Items folder. I recommend creating a folder to use for cleanup, at least until you see how this feature works.
Along with setting the folder to be used for cleanup, you can:
- Recreate the folder hierarchy under the Clean up folder. (This makes it easier to find all of the original messages, if needed.)
- Don't move unread, categorized, flagged, or digitally signed messages.
- Keep (don't move) the original when you reply and modify the quoted message, such as to quote "inline" or trim the original message in the reply.