This excerpt taken from the WPI 8-K filed Sep 7, 2006.
10. GENERAL PROVISIONS.
10.1 Notices. Any notices provided hereunder must be in writing and shall be deemed effective upon personal delivery (including, personal delivery by facsimile transmission) or the third day after mailing by first class mail, to the Company at its primary office location and to Executive at his address as listed on the Company payroll (which address may be changed by written notice).