Use this tool to view all messages in a conversation together, and use the cleanup function to delete the duplicate text. This way you will keep all your emails (sent and received) on a topic in one place, and save space in your inbox by removing identical text included in replies. Here's how to do it:
Set your emails to conversation view
Open Outlook. In the View tab at the top of the screen, check the Show as Conversations box. This will group together emails by conversation. You can play around with the Conversation Settings to see what works best for you. We suggest selecting Show Messages from Other Folders to include your sent mail as well.
Messages in a conversation will now appear as a single item in your inbox viewing pane. To see all the messages in a thread click the arrow to the left. If you did not select Always Expand Conversations in Conversation Settings you will need to click this arrow twice to see the full thread, including your sent items.
On the Home tab, select Clean Up. You can choose to clean up a single conversation, the current folder, or the current folder and any subfolders. If you want to change cleanup settings, click Settings when the dialog box appears.
Scroll down to the Conversation Clean Up settings and select options you would like. We suggest selecting the last option, "When a reply modified a message, don't move the original" to ensure that if someone modifies the sent text in a reply the original version is not lost.
Note that Conversation Cleanup does not run automatically, so you will have to remember to do so periodically. One idea to help you remember is to set a recurring appointment in Outlook.