Daemon which provides TLS client policy for Postfix via socketmap, according to
domain MTA-STS policy. Current support of RFC8461 is limited - daemon lacks
some minor features:

  - Proactive policy fetch
  - Fetch error reporting
  - Fetch ratelimit (but actual fetch rate partially restricted with cache_grace config option).

Server has configurable cache backend which allows to store cached STS policies
in memory (internal), file (sqlite) or in Redis database (redis).

WWW: https://pypi.python.org/pypi/postfix-mta-sts-resolver