knowledge base

Details:

Folders must be copied one at a time.

In the Old mailbox, check the box next to the folder you wish to export
Choose "Download Folder(s)" from the drop-down list
Select a filename. If the server suggests a filename with a php extension, 
there is something wrong with the folder. It will never export properly. I don't know 
why.
Copy the name of the mailbox into the clipboard to save some typing and 
possible spelling errors.
Create a folder in the new mailbox. The new folder name must be preceded by 
a dot (.)
Check the box next to the new folder and choose "Import 
Messages"
It may take a few seconds to upload the email if there are many messages in 
it.