(1) The notice of termination shall be served upon each grantee whose rights are being terminated, or the grantee's successor in title, by personal service, or by first class mail sent to an address which, after a reasonable investigation, is found to be the last known address of the grantee or successor in title.
(2) The service provision of 17 U.S.C. 203, 304(c), or 304(d), whichever applies, will be satisfied if, before the notice of termination is served, a reasonable investigation is made by the person or persons executing the notice as to the current ownership of the rights being terminated, and based on such investigation:
(i) If there is no reason to believe that such rights have been transferred by the grantee to a successor in title, the notice is served on the grantee; or
(ii) If there is reason to believe that such rights have been transferred by the grantee to a particular successor in title, the notice is served on such successor in title.
(3) For purposes of paragraph (d)(2) of this section, a reasonable investigation includes, but is not limited to, a search of the records in the Copyright Office; in the case of a musical composition with respect to which performing rights are licensed by a performing rights society, a reasonable investigation also includes a report from that performing rights society identifying the person or persons claiming current ownership of the rights being terminated.
(4) Compliance with the provisions of paragraphs (d)(2) and (d)(3) of this section will satisfy the service requirements of 17 U.S.C. 203, 304(c), or 304(d), whichever applies. However, as long as the statutory requirements have been met, the failure to comply with the regulatory provisions of paragraph (d)(2) or (d)(3) of this section will not affect the validity of the service.