Blocking email addresses will not only prevent the blocked emails from showing up in your inbox, but it’ll ensure that you don’t get a notification badge when you receive emails from blocked senders too. When you get emails, you also get notification badges that stick out in your Mac’s Dock. The divider simply wouldn't appear when dragging.If you use Apple’s Mail app that comes pre-installed on macOS devices, you may already know that it’s well-integrated into the operating system. The pointer's appearance changed when placed near the edge of the window, cueing me that it was properly positioned and ready for me to drag. And now my friend's problem had also become my problem. Satisfying, that is, unless the divider can't be dragged back to the left. The divider will attach to the right edge of the window with a satisfying snap. If you drag the divider between the message list and preview all the way to the right, the preview will be hidden. You can also drag the vertical dividers that separate the three columns left or right to adjust the widths of the three columns. In Catalina, you can show and hide the right-hand column by choosing Show Side Preview from the View menu. You can come close to emulating the classic layout in Catalina by choosing some options in the View menu, but by default, the Mail app presents a three-column view: mailboxes on the left, a message list for the selected mailbox in the middle, and a preview of a selected mail message the right.

Mail viewing preferences in Catalina (Image credit: iMore)

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