From the action grid:
1. If you have the action grid selected as one of your swipe actions, swipe the message you would like to mark as unread and open up the action grid.
2. Click on “Mark Unread” or “Mark Read”.
Note: If you do not see these options, please swipe left to reveal the second page of the action buttons
From the message details:
1. Open up the email message you would like to change to read or unread.
2. Click on the action button in the top right corner.
3. Swipe the page to the left to view the second page of actions.
4. Click on “Mark Unread” or “Mark Read”.
You can also change your swipe settings so that "mark as read/unread is an option. To do so:
1. Open up the app settings.
2. Select “Swipe actions” from underneath the Customize section.
3. Select the swipe you would like to change.
4. Select “Read/Unread” from the options.
5. Click on “Save.”