The "Save Window SIze and Position" for the Mailbox window should also save the column widths.
The "Save Window Size and Position" should also save the column widths in the Mailbox window. Every time I select "Read" to open the Mailbox, I have to make the "My Mail Folders" column wider to fit all my folder names, and I have to make the "From" column wider to see more of the email addresses. Other apps and programs do this without the user even asking to save them. They just keep the widths the same as they were left when last used.