41 C.F.R. § 105-70.008 Service of complaint.
Title 41 - Public Contracts and Property Management
(a) Service of a complaint must be made by certified or registered mail or by delivery in any manner authorized by Rule 4(d) of the Federal Rules of Civil Procedure. Service is complete upon receipt. (b) Proof of service, stating the name and address of the person on whom the complaint was served, and the manner and date of service, may be made by— (1) Affidavit of the individual serving the complaint by delivery; (2) A United States Postal Service return receipt card acknowledging receipt; or (3) Written acknowledgment of receipt by the defendant or his representative.
Title 41: Public Contracts and Property Management
PART 105–70—IMPLEMENTATION OF THE PROGRAM FRAUD CIVIL REMEDIES ACT OF 1986
§ 105-70.008 Service of complaint.

