Please first make sure that Mailbutler is installed.

1. Open Apple Mail.

2. Click Mail in the menu bar on the top left of your screen.

3. Go to Settings/Preferences > General.

 

4. Click Manage Plug-ins.

5. Activate Mailbutler.mailbundle by checking the checkbox.

6. Click Allow Access.

7. Click Apply and Restart Mail.

8. You will now see Mailbutler's features and the Mailbutler sidebar in Apple Mail.