Send Mail using current users mailfile

I was wondering if there is a way that when someone clicks a mail forward button that it can grab the current users mail file and send the mail using that rather than the mail file that is in the location document?

I hope i am explaining this right.

Subject: Are you referring to the from…

Are you referring to the from field? Meaning you want to message to appear it came from userB versus userA? Please explain.