(1) Unless the plaintiff has elected certified mail service or designated delivery service, the summons shall be served by the sheriff of the county where service is made, by a person authorized by section 25-507 or otherwise authorized by law, or by a person, corporation, partnership, or limited liability company not a party to the action specially appointed by the court for that purpose.

(2) Certified mail service or designated delivery service shall be made by the plaintiff or plaintiff's attorney.