How can I use different responding email addresses?

[greydarrah]

I have 2 different POP email addresses that are both forwarded to my gmail account. If I'm on a PC, logged into gmail, when I either create or respond to an email, I can choose (from one of my 2 POP addresses) who it says the email is from. How can I set up a Droid X to let me make that choice? Will K9 or any of the other email apps let me do this?

 

[greydarrah]

Is this impossible, or did I post it in the wrong section.