Is that necessary? If you don't think so, Outlook can do something about this wasteful proliferation. It will not prevent messages from being quoted; instead, it will remove the quoted messages in one fell swoop.
Streamline Conversations in Outlook
To clean up conversations in Outlook and remove redundant messages:
- Go to the Home tab in the main Outlook window ribbon.
- Click Clean Up in the Delete area.
- Select how much to clean up from the menu:
- Clean Up Conversation - remove messages that are fully quoted in others from the current conversation.
- Clean Up Folder - remove all redundant emails from the current folder.
- Clean Up Folder & Subfolders - remove fully quoted messages from the current folders and all folders beneath it in the folder hierarchy.
- Click Clean Up if you are asked to confirm your action.
To streamline the current conversation fast in Outlook:
- Press Alt-Del.
- If prompted, select Clean Up.