rcptto_list

# File lib/net/smtp.rb, line 840
    def rcptto_list(to_addrs)
      raise ArgumentError, 'mail destination not given' if to_addrs.empty?
      ok_users = []
      unknown_users = []
      to_addrs.flatten.each do |addr|
        begin
          rcptto addr
        rescue SMTPAuthenticationError
          unknown_users << addr.dump
        else
          ok_users << addr
        end
      end
      raise ArgumentError, 'mail destination not given' if ok_users.empty?
      ret = yield
      unless unknown_users.empty?
        raise SMTPAuthenticationError, "failed to deliver for #{unknown_users.join(', ')}"
      end
      ret
    end