How do I open/close the Mailbutler Sidebar on macOS Sonoma and higher?

To open the Mailbutler Sidebar, click the Mailbutler icon at the top of your Apple Mail window.
To close the Mailbutler Sidebar, click the close button.



Once opened/closed, the Mailbutler Sidebar will stay opened/closed by default.

For instructions on how to attach/detach the Mailbutler Sidebar on macOS Sonoma and higher, head to this article.