Unless expressly otherwise agreed between the parties, every notice or response required by this chapter to be served upon the City or the Grantee shall be in writing, and shall be deemed to have been duly given to the required party when placed in a properly sealed and correctly addressed envelope: (i) upon receipt when hand delivered with receipt/acknowledgment; (ii) upon receipt when sent certified, registered mail; (iii) within five business days after having been posted in the regular mail; or (iv) on the next business day if sent by express mail or overnight air courier.