hi, I need this and other users could need, you can't force to write to Maildir.
So, PLEASE, next time don't change the Procmail config anymore, otherwise if an Admin sets those variables to /var/spool/mail/$LOGNAME, when the update is done the emails will be written on Maildir, instead.
Please, you have to avoid this behavior.
If you think that something on config should be changed, you should do a backup of the conf (as usual) and leave the current conf in place, and IF NEEDED notify the users about this.
Thanks Best Regards