Gareth, you use

ACTION="mailto:..."

in your HTML form.

This works only on a few selected operating systems with a few selected combinations of web browsers and email clients.

Problems can be:
no email sent because no email client on the surfer's computer
no data in the email
only partial data in the email
...

It is much more reliable to use a server-based technology to send such form results. If your provider does not allow you to use CGI/PHP/ASP/JSP/Servlet/... there are some free formmail providers you could use. Ask google for "free formmailer" and take your pick.

MudGuard