The collector shall give notice of every sale by posting advertisements thereof in 2 or more public places in the town at least 25 days before the sale, exclusive of the day of posting and the day of the sale, in which shall be stated the name of the owner or of the person to whom the same was taxed, the description of the property as recorded by the selectmen, the amount of the tax, interest due thereon and costs and fees incident to advertising and posting, and the place, day and hour of the sale. He shall also, before the posting, but not more than 30 days before the posting, send notice by registered mail to the last known post-office address of the owner or of the person against whom the tax was assessed.