Airbnb will start pestering hosts in its hometown of San Francisco to register with the city and report on their rental activity each quarter, executives wrote in two letters to the city obtained by Bloomberg. While a November ballot initiative to curb year-round rentals in the city failed, Airbnb continues to face pressure. The moves in San Francisco, which aim to show the company is willing to work with the local government, could be a hint of what's to come in other cities around the U.S. Twice a month, Airbnb will send e-mails and letters to hosts' homes in San Francisco urging them to register, according to a letter by Patrick Hannan, Airbnb's new public policy manager who previously led the campaign against the proposed law in San Francisco. The company will also run advertisements to encourage hosts to register, Hannan wrote.