At the top of the page, a notice tells you when you have received new messages.
Reading
The Mail page separates received and sent messages. You can reply, delete a message, or delete them all.
Writing
Enter the player's name as recipient, a subject, your message. To write to your whole alliance at once, type a star (*) as the recipient.
Mail is private. The forum and the public message on the game's home page are for everyone.