Sending email through specific server

Hiya

I am trying to send mails from a website that has been set up
for a project. The emails will not send to outside of the network
because of the firewall.

The code is as follows:
If Len(HRM & "") > 0 then
Set Mail=Server.CreateObject("CDONTS.NewMail")

Mail.To= HRM
Mail.From = "test@test.com"
Mail.Subject="Thank you for showing interest in our HRM survey"
mail.body = "Hello, this is to be filled out" & vbcrlf
Mail.Send()
Set Mail=nothing
end if

NOTE: HRM is a email address taken in from a form on the site.
This code works for email addresses inside the network. I need to
specify the server and make it go through the network server and
then onto hotmail, yahoo, etc. (I think!!) Does any know if I am
on the right track and if so hwo I go about this?
Any help would be greatly appreciated
Regards
Kar