All notices, applications, complaints, findings of fact, opinions and orders required by this title to be served may be served by mail and service thereof shall be deemed complete when a true copy of such paper or document is deposited in the post office properly addressed and stamped.
[ 1961 c 14 § 80.04.075. Prior: 1933 c 165 § 7; RRS § 10458-1. Formerly RCW 80.04.370.]