Please follow these steps in order to be able to rotate images contained within email messages. This will work with Outlook 2010 to 2016.

  1. Double click to open the message
  2. Outlook 2010/2013: Enable Edit Message mode Do this using the Move group, Actions menu, Edit message command. 
  3. Use the Edit message command to make the message editable

  4. Double click to open the attached image
  5. The image will open using the application assigned the image file type. This program needs to have the ability to rotate images and save changes.
  6. Rotate the image then save changes.
  7. Close the image editor
  8. Save and close the message
  9. Select the image and verify it is rotated. In some cases, you need to select a new message in the message list then reselect the message you just edited to see the changes.