29.4 All Correspondence to be exchanged between the parties shall be served by delivery in person confirmed by the issuance of a receipt or sending by registered air mail or courier or by electronic means confirmed by a receipted or registered letter for notices. Notices delivered in person shall be effective upon delivery thereof. Notices sent by registered air mail shall be deemed to have been served following the expiration of 7 (seven) days after posting unless the contrary is shown.