See the thread in the Cool Hacks forum. This is the issue I was talking about with blaine.
It is because in users.php, createuser(), if a bad email is entered, it only shows the newuserform().
You need to check for a custom_userform(). Around line 535 of users.php is this:
} else {
$retval .= COM_siteHeader (\'Menu\')
. newuserform ($LANG04[18])
. COM_siteFooter();
}
You need to change to:
} else {
$retval .= COM_siteHeader (\'Menu\');
if ($_CONF[\'custom_registration\'] AND (function_exists(custom_userform))) {
$retval .= custom_userform (\'new\', \'\', $LANG04[18]);
} else {
$retval .= newuserform ($LANG04[18]);
}
$retval .= COM_siteFooter();
}