How to delete mail in macOS High Sierra’s Mail app

There are several ways to delete mail in the Mail app of macOS High Sierra.  To delete a message from a Mail notification or with a swipe, the “Move discarded messages” option in Viewing preferences in Mail must be set to Trash; otherwise, the message is archived.

Viewing Prefs.jpeg
  • In a Mail notification: Move the pointer over the notification, then click Trash.
  • In the Message viewer: Do one of the following:
  • Swipe left with two fingers, then click Trash, or swipe all the way to the left until the message disappears.
  • Move the pointer over the message header, then click the Delete button (it looks like a trashcan) that appears.
  • Select a message in the list, then click the Delete button in the Mail toolbar.