You can mark an email as read or unread in a few ways:
- From the mail-view 3-dot menu: open the email, tap the 3-dot menu, and choose Mark as Unread.
- From the Mail List (mobile): swipe the email and choose Read / Unread. On the default setup this is a swipe to the right; if you have customized your swipe menu it may be on the left instead.
- From the Mail List (desktop): right-click the email and select Mark as Read or Mark as Unread.