BlackBerry:

NOTE: This article does not apply to sites running NLES v4.5.0 and device client v4.5.0 and later. Reply To is synchronized to the device and displayed when issuing a reply.

If you are using a BlackBerry and receive an email notification from a user that has a Reply To address set up, when you go to reply to the message on the device you will see the FROM address populate instead of the REPLY TO address. This should not be a concern because when the email is sent it will be sent to the correct REPLY TO address.