POP Peeper FAQ
Why don't Imap messages get marked as read after I read them in my email client?
POP Peeper will only access the "read" status of a message when the message is new to POP Peeper. Once a message is listed in POP Peeper, the read status will not be updated from the server. This behavior is due to the additional methods of message retrieval that POP Peeper provides. There are plans to improve the behavior of the read status in a future version.