Can I use WW Ipstuff to send email if my email server is setup to only send mail after verfication (use passwords) (stop the spammers)????

I can send email fine as long as the server is open to relay.

I use Imail which is a good email server. If I can not use it, what SMTP server can setup that is small, cheap and will only send email from ONE address or one IP????

THANKS