Folders in the folder area are displayed in simply ASCII sort order. A trick I use to get the sort order I want is to add dashes to the folder names I want early in the list so that the other folders naturally sort after, ala:
-InBox- -Lists- -Odd- -Rcvd- ... Drafts Errors OutBox
.mh_profile Folder-Order
You can also use the Folder-Order: keyword in your .mh_profile to instruct exmh where to place your folders. Any folder not included in this value will sort alphabetically afterwards.
Folder-Order supports patterns. I use * to collect all the ones I don't mention specificially, and put all the ones I want to avoid after that. Here is my setting - note that it is all on long line in your .mh_profile file (Brent Welch)
Folder-Order: urgent panasas bugs inbox webmaster family book tcl/url p4 footbag tcl tcl/* exmh exmh/* * default cron badaddr footlist junk OLD