Where my Mail go iPhone

I have a few Email accounts on my iPhone, Gmail, Exchange, and a couple of regular Email accounts for Domains I own.
If I send an Email through my Exchange or Gmail accounts, a copy is also available on Gmail on the Web or through Outlook at work in addition to being on my iPhone.
However, if I send an Email through my iPhone via my own personal Domain Name accounts, there is no record of my ever sending the Email: its neither on the iPhone Sent Items nor is it on the Web? Where does a copy of it go if I want to re-read it, check it, or resend it?
Many thanks
Brian
HP Other OS Vista