Scanning a Maildir++ box for new folders will fails to recognize previously found folders as such, i. e. it will add every folder again and again.
The attached patch for maildir-0.24.4cvs18 seems to fix the problem.
Created attachment 1167 [details]
Suggested fix for the problem
the maildir plugin is no longer supported or developed. Closing this until a new maildir plugin developer comes along.