How to add contacts automatically as and when i type in the mail application (inside the to field)

How to add contacts automatically as and when i type in the mail application (inside the to field)

How to add contacts automatically as and when i type in the mail application (inside the TO field).
the new contacts which i type in the (TO field of the mail application) has to be added automatically to my contacts.?
how do i do this??
Plz reply ASAP.