mastodon/config/initializers/blacklists.rb

# frozen_string_literal: true

Rails.application.configure do
  config.x.email_domains_blacklist = (ENV['EMAIL_DOMAIN_DENYLIST']  || ENV['EMAIL_DOMAIN_BLACKLIST']) || ''
  config.x.email_domains_whitelist = (ENV['EMAIL_DOMAIN_ALLOWLIST'] || ENV['EMAIL_DOMAIN_WHITELIST']) || ''
end