To do this:

From the Inbox, Press CONTROL + N. A message window opens with the cursor in the "To" box.
Type the email address of the recipients. Separate each email address with a semi colon.
TAB to the "CC" box and type in any additional email addresses to receive a copy of the email.
TAB to the "Subject" box and type in a subject for the email.
TAB to the message body and type a message.

When you are ready to send the email, press ALT + S. Mail closes the message window and sends the email. It is then sent the next time you go online.