Whenever a notice is required to be given under this Code, unless different provisions are otherwise specifically made in the Code, such notice may be given either by personal delivery thereof to the person to be notified or by deposit in the United States mail in a sealed envelope, postage prepaid, addressed to such person to be notified at his last known business or residence address as the same appears in the public records of the City or other records pertaining to the matter to which such notice is directed. Service by mail shall be deemed to have been completed at the time of deposit in the post office.