The publication of the ordinance and notice shall be at least ten days prior to the time fixed for the consideration of said report and the further consideration of the said ordinance for final passage. At least one week prior to the time so fixed, a copy of the ordinance, together with a notice of the introduction thereof, of the filing of the map and report, and of the time and place when and where the governing body will meet to hear and consider any objections to said report or improvement, shall be mailed to every person whose lands may be affected by such ordinance or any assessment which may be made in pursuance thereof, so far as the same may be ascertained, directed to his last known address. Failure to mail such notice shall not invalidate any ordinance, proceeding or assessment.