senders:
  - re: 'sender1\@example\.com'
    key: 'api token'
  - re: 'sender2\@example\.com'
    key: 'api token'

recipients:
  - re: 'recipient1\@example\.com'
    keys:
      - 'user token 1': 'my device'
      - 'user token 2'
  - re: 'recipient2\@example\.com'
    keys:
      - 'user token'