Suddenly Cron wasn’t running my mail script; I verified that the script itself was still working, so than I began the venture into the unknown: how to debug Cron? Serverfault has a good answer. Everything seemed to checkout, and I verified that it was working to write to a tmp file. The file was being written. Finally, by removing the line that smothers output to /dev/null I was able to find the problem: the need for an absolute path name (as evidently the Cron user couldn’t run getmail without a full path).