// Evalúa posibles errores en el formulario de contacto en español
function ChkForm(form){
	// CAMPO NOMBRE Y APELLIDOS
	if (form.from_name.value=="") { alert("Please, type your name"); form.from_name.focus(); return false; }

	// CAMPO EMAIL
	if (form.from_email.value == "") { alert("Please, type your e-mail address"); form.from_email.focus(); return false; }
	<!-- Verifica que  contenga UNA y sólo UNA arroba
	num_arrobas=0;
	for (var i=0; i < form.from_email.value.length; i++) {
		chr=form.from_email.value.substring(i,i+1);
		if (chr=="@") num_arrobas++;
		if (chr=="," || chr=="<" || chr==">" || chr=="*" || chr=="?" || chr=="¿" || chr=="!" || chr=="¡" || chr=="ñ" || chr=="Ñ") { alert("ATENTION!: You must type a valid e-mail address!"); form.email.value=""; form.email.focus(); return false; }
	}
	if ( (num_arrobas>1) || (num_arrobas <1) ) { alert("ATENTION!: You must type a valid e-mail address!"); form.from_email.value=""; form.from_email.focus(); return false; }
	<!-- Verifica que no contenga '.' antes ni después de la '@'
	arroba_pos=+form.from_email.value.indexOf("@");
	if ( (form.from_email.value.charAt(arroba_pos-1) == ".") || (form.from_email.value.charAt(arroba_pos+1) == ".") ) { alert("ATENTION: You must type a valid e-mail address!"); form.from_email.value=""; form.from_email.focus(); return false; }						
	<!-- Verifica que no contenga menos de un punto despues de la @
	num_puntos=0;				
	for (var i=arroba_pos; i < form.from_email.value.length; i++) {
		chr=form.from_email.value.substring(i,i+1);
		if (chr == ".") num_puntos++;
	} 
	if ( (num_puntos <1) ) { alert("ATENTION!: You must type a valid e-mail address!"); form.from_email.value=""; form.from_email.focus(); return false; }

	// CAMPO ASUNTO
	if (form.to.value=="") { alert("Please, select a subject for your message"); form.to.focus(); return false; }
	
	// CAMPO MENSAJE
	if (form.message.value=="") { alert("Please, type your message"); form.message.focus(); return false; }
}