(b) Manner of service. The notice provided for in paragraph (a) of this section shall be accomplished by: (1) Sending a letter by first class mail, properly stamped and addressed, to the tenant at his or her address at the project , with a proper return address, and (2) serving a copy of the notice on any adult person answering the door at the leased dwelling unit , or if no adult responds, by placing the notice under or through the door, if possible, or else by affixing the notice to the door. Service shall not be deemed effective until both notices provided for herein have been accomplished. The date on which the notice shall be deemed to be received by the tenant shall be the date on which the first class letter provided for in this paragraph is mailed, or the date on which the notice provided for in this paragraph is properly given, whichever is later.