By Anonymous (not verified) updated on 10/18/2009
Even though there is no Resend button on the iPhone, there is a workaround. Open the Sent folder in Mail and select the message you want to resend. Then tap the folder button on the bottom taskbar (second from the left) and then the Drafts folder. This places the message in the Drafts folder. From there, you can open it up, enter an address, and send it again.