I have an oldish computer that is running Aplle's Mail program with a large amount of mail coming in (the current number of emails on the computer is in the tens of thousands). Recently it has started to get emails mixed up. When you view all the emails in a table, you will see the summary information (ie, who it was sent from, what the subject is and the time etc) but when you click on the row to show the contents, it will be the wrong email. When I view the inbox from a web browser I do not experience these problems. I have tried rebuilding the mailbox, but although that fixes the problem, it is not long before the incoming mail gets mixed up again.
Has anyone had any experience with this? I guess it is due to the volume of emails and if I set up some sort of archive system it will avoid the problem. But I was just hoping it could work as it is.
I have decided to try and format and reinstall everything again. I will update this with the result (it will take some time).