Ymail is a domain offered by Yahoo Mail. The domain was introduced in 2008 as an effort to attract new users and hold onto existing ones who were leaving for other providers. Ymail uses the same interface as Yahoo Mail.
Yahoo Mail also introduced Rocketmail as part of its services in 2008. The new domains gave users a chance to get the email addresses that they wanted instead of one they settled for when their preferred user name was unavailable. Users can access their Ymail and Rocketmail accounts from the Yahoo Mail homepage. Rocketmail was part of an acquisition in 1997 of Four11 for $92 million.