ORS 91.110: Notices to be in writing; how served.

All notices required by ORS 91.050 to 91.070 and by ORS 105.120, must be in writing and must be served upon the tenant by being delivered to the tenant in person or by being posted in a conspicuous place on the leased premises in case of the absence of the tenant, or by being left at the residence or place of abode.