Irvine-based YouMail, which is developing a customized replacement voice mail service, said today that it has partnered with Salient Media, a production and licensing firm in the comedy business. YouMail said that Salient's entertainers will offer exclusive, comedic voice mail greetings for YouMail. According to the firm, it will start by offering free greetings from comedian, actor, and rapper Katt Williams. Financial terms of the partnership were not disclosed. YouMail operates a service which allows cell phone users to provide customized voice mail greetings depending on who is calling you; the firm recently raised $4.5M in funding from VantagePoint Venture Partners.