this allows us to forward email to others via the filter servers.

hosts.yml.default.

in particular:
 smartctl:
      interval: 10
      enabled: true
      checks:
        - path: /dev/sda
        - path: /dev/sdb
        - path: /dev/sdc
        - path: /dev/sdd
          count_exceptions:
            197: 3

Gets incorrectly added as:

- path: /dev/sdc
- count_exceptions:
  197: 3
- /dev/sdd

we're running nginx on these servers to the relay certs are handled by
our key server.

address.

This helps when a particuular domain name cannot be delivered via a
given transport.

also removed no longer needed coturn hacks.