How can i automatically add the persons that send email to me into my contacts in Gmail or yahoo?

i want to have automatically their mail address in my contacts because it takes a long time to enter them manually.

How can i automatically add the persons that send email to me into my contacts in Gmail or yahoo?
right under the sender's email, there should be options, or a "More Options" tab, click on that and click Add Sender to Contacts.
Reply:iN YAHOO IT IS EASY. WHEN U RECEIVE AN EMAIL FROM ANYBODY REPLY TO THEM , AFTER U HAVE SENT A REPLY, A WINDOW WILL OPEN ASKING WHETHER U SHOULD ADD TO ADDRESS BOOK , THEN U CAN JUST CLICK THE RIGHT BUTTONS AND U WILL HAVE DONE THE NEEDFUL.IT CANT BE DONE AUTOMATICALLY.
Reply:first add those contacts in address book and ull have option 'insert address' while sending mails..