Marissa Mayer's tenure as CEO of Yahoo has benefited the company immensely in order to bring around the company's corporate culture, rejuvenate its products, and refresh its image. But a new redesign of Yahoomail and the long-running outage for some some Yahoo e-mail users is casting a dark shadow over a perceived turnaround at the once-mighty Internet player. Announced last December, the first e-mail overhaul rolled out to all users in June. The reception was lukewarm because it was just a cosmetic redesign.