Bukkit

Here's an overview about all the commands and the permissions:
The permission nodes are written italic.

• /simplemail
  Shows information about the plugin.
  
• /simplemail reload
  Reloads the configuration and the mails file.
  simplemail.reload
  
• /mail send <player> <message>
  Sends the <message> to the <player>
  simplemail.mail
  People with simplemail.mail.free can send messages for free!
  
• /mail read
  Displays the mails the player has.
  simplemail.mail
  
• /mail clear
  Clears the player's mails.
  simplemail.mail