When I delete 50 messages, it start open quickly.
I think that says it all. If you want to keep all 64004 messages I suggest renaming the current COPYSELF folder to something like COPYSELF_Archive, creating a new COPYSELF folder, and then setting the new folder as the destination for copies to self. You will need to set the new folder as the destination even if the folder name is the same (be sure to use the "Select folder" button).
As a side note, the copyself folder created by default is called "Copies to self". There is something unique about this folder that causes it to sort to the top of the folder list. I can provide details on how to restore that default folder if you are interested.
[quote="pid:55602, uid:4028"]When I delete 50 messages, it start open quickly.[/quote]
I think that says it all. If you want to keep all 64004 messages I suggest renaming the current COPYSELF folder to something like COPYSELF_Archive, creating a new COPYSELF folder, and then setting the new folder as the destination for copies to self. You will need to set the new folder as the destination even if the folder name is the same (be sure to use the "Select folder" button).
As a side note, the copyself folder created by default is called "Copies to self". There is something unique about this folder that causes it to sort to the top of the folder list. I can provide details on how to restore that default folder if you are interested.