mastodon/config/settings.yml

# config/app.yml for rails-settings-cached
defaults: &defaults
  site_description: ''
  site_extended_description: ''
  site_contact_username: ''
  site_contact_email: ''
  notification_emails:
    follow: false
    reblog: false
    favourite: false
    mention: false
    follow_request: true
  interactions:
    must_be_follower: false
    must_be_following: false
development:
  <<: *defaults

test:
  <<: *defaults

production:
  <<: *defaults