Copying "sent" mail from "Mail" account into Yahoomail account
Whenever I send mail using "Mail" account (the account with the halk on a stamp at the bottom of the dock) I the mail that I send on that account is not automatically sent to my "Yahoomail" account (online, www.yahoomail.com). The only way I can get it moved is if I right click on the message and select "Copy to, Yahoo, sent" which can get tedious after a while. Needless to say, having a way to get the mail automatically moved to my Yahoo! account would be great.
MacBook Pro (13-inch, Mid 2012), OS X Mountain Lion (10.8.1)