Yes, I'm sure of that.
The form has Server Validation on it, on the same page, because it's an UPDATE form and I've made sure that the Server Validation behaviour code is above the UPDATE behaviour code so that it runs before the UPDATE occurs.
The form isn't submitting directly to the page that sends the e-mail because it's doing a Server Validation and an UPDATE first, and then redirecting, via the UPDATE behaviour, to the page that sends the e-mail which I've simplified to:
$UpdateGoTo = "reserve-whisky-cask-confirm.php?wbid=".($rsCASKINFO->getColumnVal("wbprodID")) ."";
I attach three pages.
reserve-whisky-cask.php - the page with the form
reserve-whisky-cask-confirm.php - the page that the UPDATE behaviour directs to.
reservecaskreceipt.php - the email template