If you are using the standard Unix Mail command then you must save the message to a file and then print the file. Figure shows an example of how to print a mail message. If you just got a new Unix account then you probably don't have any mail yet. You will be prompted for a subject. After entering your subject line, everything you type goes in the mail message.
Some commands are acceptable in a mail message, if they occur at the beginning of a line.
Of course if you really want to communicate by mail you have to know the intended recipient's address.