Opening sent mail results in return receipt

I have several users experiencing the following:

  • User opens a message in their Sent view

  • A return receipt for that message instantly deposits in their Inbox (this does not happen for all messages, but happens regardless of whether a return receipt was originally requested)

  • When the message is closed, the sent message is marked unread and the view automatically switches to the Inbox

Ideas appreciated.

Subject: Opening sent mail results in return receipt

Did you solve this problem? I have the the same problem.