Method of service of documents.

Except as otherwise provided by a specific regulation, notices, determinations, findings of fact, opinions and orders of the Commissioner, and any document filed by a party, may be personally served upon a party or served by United States mail, facsimile or electronic mail. If served by United States mail, service shall be deemed to be complete when a true copy of the document, properly addressed and with postage paid, is deposited in the United States mail.