I'm using courier imap. When a mail client creates a new folder, it's created on the filesystem with 640 permission. I need it to be writable by the group, or 660. I currently have /etc/courier/imapd IMAP_UMASK=007, but that's not enough.

I'm not sure what else to try. Any ideas? I'm using ubuntu server 12.04.

EDIT: I added a 50pt bounty to this. For an acceptable answer, I need a way to make it work from a package in a standard repo. If I download source and compile it myself, it won't be automatically kept up to date with security fixes.

If I don't find a better answer, I'll add code to the admin script to call another sudo approved script to chmod -R the whole directory before every change. But this is kind of hack-ish.