Rather than running the patched procmail, you might consider using safecat to deliver to your inbox. That allows you to use the latest procmail without waiting for the maildir patches to be applied to it. Procmail's maildir support does not comply with Dan's algorithm, and so does not offer the reliability promised by maildir delivery. Procmail plus safecat has always offered reliable maildir delivery. If you write CGI applications to collect data over the World Wide Web, you might find safecat useful.
Web applications suffer from two major problems.
Maybe the database activity completes. Maybe the CGI script is killed, leaving the DB in an inconsistent state. Consider the following strategy. Make your CGI script dump its request to a spool directory using safecat. Immediately return a receipt to the browser.