37 CFR § 42.205 - Service of petition.
(a) The petition and supporting evidence must be served on the patent owner at the correspondence address of record for the subject patent. The petitioner may additionally serve the petition and supporting evidence on the patent owner at any other address known to the petitioner as likely to effect service.
(b) Upon agreement of the parties, service may be made electronically. Service may be by Priority Mail Express® or by means at least as fast and reliable as Priority Mail Express®. Personal service is not required.