Notices and all other communications provided for in this Agreement shall be in writing and shall be deemed to have been duly given when delivered by (i) personal delivery, (ii) a nationally-recognized, next-day courier service, or (iii) first-class registered or certified mail, postage prepaid addressed to Employer at its principal office an d to Employee at the address listed on Employee’s invoices, provided that all notices to Employer shall be directed to the attention of the Chief Executive Officer, or to such other address as either party may have furnished to the other in writing in acco rdance herewith, except that notice of change of address shall be effective only upon receipt .