You can set up Mail Tool so that you record a copy of each email message you send. To do this, follow these steps:
A Properties window appears.
The properties choices for the Compose Window appear in the Properties window.
In the text field labeled Logged Messages File, type the name of a file in which you would like to log copies of your mail messages.
For instance, to save the mail in an invisible file in your home directory, you could name the file $HOME/.mail.save.
Click SELECT on the Apply button at the bottom of the Properties window.
Now, when you send a message, a copy is logged in the file you created; additional messages you send are appended to the end of the file.