This function does not delete the Unread Messages also, it only deletes them. I then have to delete the read ones too. Is this really how it is supposed to work? The also is supposed to be there isn't it?
Yes, it does delete them, but not "also". You need to run the function twice - or at least I do [same as guessme] - once with the checkbox ticked [that deletes the unread messages] and another time without [to delete the read messages].