Twitter Inc (NYSE:TWTR) has launched a new advertising program that lets advertisers target e-mail addresses and user IDs specifically. The service is called Tailored Audiences. Twitter revenue product manager Kelton Lynn said that advertisers can set up ad campaigns for Tailored Audiences using customer relationship management databases or a list of Twitter usernames / user IDs. Users can opt out of the program in their settings. There is a minimum audience size to avoid overly specific targeting.