I was using Zoom the other day (like we do), helping a friend with the Mail app on his Mac running macOS Mojave. The viewport only displayed a list of mailboxes and a very large list of messages. There was no third column on the right side of the window to display email message previews.
No problem. Simply swipe left from the right edge of the mail viewer window to expose the third column. Except…it didn’t work.
We’ve tried playing around with various menus and preferences and going back to the classic layout (remember, this is Mojave we’re talking about), all to no avail.
How the Mail app moved from Mojave to Catalina
If you’ve played around with Apple’s Mail app in macOS Catalina, you might know that a few preferences have changed. The classic layout (mail list on top, message preview on bottom) was available as a checkbox option in Mail’s display preferences in macOS Mojave:
But this option has been removed in Catalina:
You can approximate the classic Catalina layout by choosing some options from the View menu, but by default the Mail app presents a three-column view: mailboxes on the left, a list of messages for the mailbox selected letterbox in the middle, and a preview of a selected email on the right.
In Catalina, you can show and hide the right column by choosing Show Side Preview from the View menu. You can also drag the vertical dividers that separate the three columns left or right to adjust the width of the three columns.
If you drag the separator between the message list and the preview all the way to the right, the preview will be hidden. The divider will attach to the right edge of the window with a satisfying snap.
Satisfactory, that is, unless the separator can be moved to the left. This is exactly what happened to me. And now my friend’s problem had also become my problem.
The pointer’s appearance changed when it was placed near the edge of the window, which told me it was correctly positioned and ready to be moved. But that was just a tease. The separator would simply not appear when moving.
So this sent me in search of the solution. And yes, the Internet is a wonderful thing.
Search the library
It turns out that fixing this problem involves a trip to the Library folder in your home directory.
- If the Mail app is running, choose Exit Mail from the Mail menu.
- Click on a black dot on your screen to switch to the Finder.
- Click on Goes in the menu bar.
To choose Library.
- Open the Containers case.
Drag the com.apple.mail folder in the office.
Now relaunch Mail. If the three-column view reappears and the Mail app works fine, you can delete the com.apple.mail folder on the desktop. Depending on how your Mail app normally displays, you may need to reset some of your display settings. It will be reset to the default view.
Did this solution work for you? Or did you find another way? Let us know in the comments below.