def to_h
      {
          config_mode: config_mode.to_s.to_sym,
          default_sender: default_sender.to_s,
          default_recipient: default_recipient.to_s,
          default_hostname: default_hostname.to_s,
          address: address.to_s,
          port: port.to_s.to_i,
          authentication: authentication.to_s.to_sym,
          ssl: ssl?,
          enable_starttls_auto: enable_starttls_auto?,
          user_name: user_name.to_s,
          password: password.to_s,
      }
    end
def to_h
      {
          config_mode: config_mode.to_s.to_sym,
          default_sender: default_sender.to_s,
          default_recipient: default_recipient.to_s,
          default_hostname: default_hostname.to_s,
          address: address.to_s,
          port: port.to_s.to_i,
          authentication: authentication.to_s.to_sym,
          ssl: ssl?,
          enable_starttls_auto: enable_starttls_auto?,
          user_name: user_name.to_s,
          password: password.to_s,
      }
    end
Converts this configuration into a hash.