function validate_required(field, alerttxt) {
	with (field) {
  		if (value==null||value=="") {
    		alert(alerttxt);
			return false;
    	}
  		else {return true;}			
  	}
}

function validate_email(field, alerttxt) {
	with (field) {
  		apos=value.indexOf("@");
  		dotpos=value.lastIndexOf(".");
  		
		if (apos<1||dotpos-apos<2) {
			alert(alerttxt); 
			return false;
		}
  		else {return true;}
  	}
}

function validate_form(thisform) {
	with (thisform) {
  		if (validate_required(visitorName, "Please tell us your Name.") == false) {
			visitorName.focus();
			return false;
		}
		
		if (validate_required(visitorEmail, "Please tell us your Email Address.") == false) {
			visitorEmail.focus();
			return false;
		}
		if (validate_email(visitorEmail, "Not a valid Email address.") == false) {
			visitorEmail.focus();
			return false;
		}
		
		if (validate_required(emailSubject, "Please tell us your Email Subject.") == false) {
			emailSubject.focus();
			return false;
		}
		
		if (validate_required(emailBody, "Please fill in your Message.") == false) {
			emailBody.focus();
			return false;
		}
  	}
}