Using the “Delete” Key with Messages - Airmail for macOS
To intentionally use the “Delete” key to delete a message and move it to the “Trash” folder, go to
Preferences > Actions > and set the Backspace field as 'Move to Trash' or as any of your desired action as
indicated in the screenshot below:
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Preferences > Actions > and set the Backspace field as 'Move to Trash' or as any of your desired action as
indicated in the screenshot below:

Updated on: 01/20/2019
Thank you!