Solution: I found a similar post in another forum from someone who solved the problem by getting procmail from the backup of his old system and installing under Mavericks.
I retrieved fetchmail, procmail, and mutt from the Time Machine, installed them. Also installed putmail.py, which had been deleted from /usr/bin. Everything works now! Problem solved.
Lessons learned: The Mavericks upgrade hoses Unix. Unix tools compiled under Mavericks may not work correctly. Unix tools from previous versions of OSX may continue to work fine.