Replying to an Email Message
To reply to an email that you have received, open the email message and then press Control + R. If you want to reply to all the recipients of a message, press Control + Shift + R.
In both cases, a new email message is created with a copy of the original message included, and with the To field completed. The Subject field is also completed with the original subject of the email and Re: added to the beginning of the subject text.
Just complete the main message text with your reply, then press Alt + S to send.
Forwarding an Email Message
To forward on a copy of a message to someone, open the email message and then press Control + F.
A new email is created as a copy of the original message. You can then enter the email address of the person you are forwarding to. The Subject field is completed already with the original subject of the email and FW: added to the beginning of the subject text.
Tab to the main part of the email to add a note onto the message, and then press Alt + S to send.