You can use the Clean Up tool on a single conversation, a folder, or a folder and all of its sub-folders. It searches for emails that are classified as redundant, which means if a message is completely contained within one of the replies, the previous message is deleted or moved to another folder, depending on your Outlook settings.
As an example, if Fred sends a message to Mary and Jane. Mary replies to both Fred and Jane and in her Outlook message body, Fred’s complete original message is included. Now, Jane sees Mary’s message and replies to both Fred and Mary. Jane’s reply includes all of the previous messages in the Conversation. This is where using the Conversation Clean Up can delete all of the messages except the last one from Jane because within that message is a copy of all of the previous messages.
First, let’s set up how we want the Conversation Clean Up to work.
In Outlook click File > Options > Mail and then move down to the Conversation Clean Up section.
By default, Conversation Clean Up deletes items, but if you want to move unneeded messages to a folder instead, click Browse and choose the folder where you want the messages to be moved to.
This is handy if you want to double-check for yourself that the messages the tool finds really are redundant.
There are many other options and if your situation is different from the defaults go ahead and change the parameters. Once the settings are the way you want, click OK.
To run the Conversation Clean up go to the Home tab and click the Clean Up drop-down menu followed by Clean up conversation.
NOTE: You can also access this menu by Right-clicking a folder or via the Folder tab.
The first time you use the Clean up conversation button a warning pops up, giving you the option to change the Settings, run the Clean Up or Cancel the operation.
If you don’t want to see these popup messages in the future click Don’t show this message again.
Next, click Clean Up to run the clean up.
NOTE: It can take a little while if you’re running it for the first time on a folder with a lot of messages, a status notice appears in the bar at the bottom of Outlook.
Once finished it won’t tell you that it’s finished as the tool is intended to compete it processing in the background. It will tell you if it can’t find any messages to clean up.
In the past when running this on a folder containing over 2000 emails, it found over 500 emails that could be deleted as they were deemed redundant.
It’s a tool worth using if you’re running out of space or tired of wading through large conversations.