Remove Duplicate
Messages

Remove Duplicate Messages removes duplicate messages from the current selection in Apple Mail. The script determines whether a message is a duplicate of another message by examining these message headers:

• MessageID
• Subject
• From
• Date

If these message headers match another message in the view, the script flags the message as a duplicate and removes it from Mail.

The script displays interactive dialog boxes that allow you to specify whether you want duplicate messages to be removed or retained, optionally prompting you for each duplicate message it encounters while scanning. You can also instruct the script to save all duplicate messages to an archive folder on disk before they are removed.

This script is provided with source code so that you may edit the script as you see fit. Read the included instructions for more information.

• Refactored duplicate message search algorithm logic for improved accuracy and efficiency.
• Fixed a bug where removed messages might not get archived if their hash signature matches a message that was previously archived.
• The script now compares the total size of all attachments in each encountered potential duplicate message. Duplicate messages with a greater total attachment size are kept, while messages with a smaller total attachment size are discarded. Thanks to Lars Boelman and Anthony Grieco for suggesting this enhancement.
• Once processing is complete, the script now clears the selection (highlighted messages) in Mail so that no messages are selected. The script does this because when Mail deletes duplicate messages, it moves them to the trash but unfortunately does not actually remove them from the current selection; so any action on messages that are still highlighted (selected) after running the script will include those deleted messages.
• Combined the three final report dialog boxes (number of duplicate messages found, removed, and the archive location) into a single dialog box to reduce the number of times users must click after the process completes. Thanks to Lars Boelman for suggesting this enhancement.