29 U.S.C. § 2107 : US Code - Section 2107: Authority to prescribe regulations

      (a) The Secretary of Labor shall prescribe such regulations as
    may be necessary to carry out this chapter. Such regulations shall,
    at a minimum, include interpretative regulations describing the
    methods by which employers may provide for appropriate service of
    notice as required by this chapter.
      (b) The mailing of notice to an employee's last known address or
    inclusion of notice in the employee's paycheck will be considered
    acceptable methods for fulfillment of the employer's obligation to
    give notice to each affected employee under this chapter.