Originally Posted by
James Nawrocki 1) go to preferences
2) In viewing uncheck classic view
3) exit preferences
4) In your mail then click on 'Mailboxes' button and toggle until it appears on the right again.
After a few hours of clicking, finally figured it out.
Not sure what you mean. Unchecking "classic view" just brings Mail back to the standard 3-column view. Clicking on "Mailboxes" just shows and hides the mailbox list on the left. Unless I'm really missing something here, you're just toggling a couple of the standard features of Mail.
What we are all trying to do is show the messages list the compact way that Classic View does, but with a 3-column layout. Basically, it's a hybrid of the two views, and it used to be possible to hack by altering Mail's preferences, but that no longer works in El Capitan.