Any notices, requests, demands and other communications provided for by this Agreement ("Notices") shall be sufficient if in writing and delivered in person or sent by a nationally recognized overnight courier service or by registered or certified mail, postage prepaid, return receipt requested, to Executive at the last address Executive has filed in writing with the Employer or, in the case of any Notice to be given to Employer, at its main offices, attention of the Chief Executive Officer, and shall be effective on the date of delivery in person or by courier or three (3) days after the date such Notice is mailed by registered or certified mail, postage prepaid and return receipt requested (whether or not the requested receipt is returned).