A free app for Android, by Yahoo Japan Corp..
Ymail is a free mobile email application for Android devices that supports both incoming and outgoing mail, as well as messaging and voice calling. The service allows users to access their accounts from any device, regardless of the operating system or device type.
Ymail supports multiple accounts and lets users add contacts to their address book to easily identify who to send messages to.
It has two display formats; conversational and list type. The conversational format allows you to exchange messages to another person in a chat-like manner. Meanwhile, the list type functions the same way as as normal mailer.
This application is compatible with outlook and docomo mail.