I want to use yahoos push mail for 2 reasons

1) it's push mail
2) spam blocker

My problem is this...
I want my work email forwarded to the yahoo address but then i want to send emails from my work address without recieving doubles of each. I know this sounds confusing basically i want to set up one email account on iphone (yahoo) but have the reply to as my work address or mask the sending yahoo adress to seem like its my work address, any tips?