Update to 20201215. From the changelog:

- qmail-qfilter-{ofmipd,smtpd}-queue: Remove after 2 years' deprecation.
  If you're using these, please switch to qmail-qfilter-queue.
- qmail-qfilter-viruscan: Optionally build with qmail-queue-custom-error
  support, returning the same error message as Russ Nelson's original
  viruscan patch.
- qmail-qfilter-queue.8, qmail-rcptcheck.8: Add an ERRORS section.

(schmonz)