You can save your E-mail into your favorite Evernote notebook without modifying a subject line. You'll get your own @enaddress.com E-mail address(es) once signed up. Just include it in your E-mail (To, CC or BCC), and you don't have to change the way how you work with an E-mail.
Since April 29, 2015, Evernote's E-mail address is available only for its Plus & Premium customers. Evernote's Pricing details are here.