var emailRegExp = /^[A-Z0-9\._\-]+@([A-Z0-9\.\-]+\.)+[A-Z]{2,4}$/i;
var message = false;

function validateTellafriend() {
	var email = document.getElementById('tellafriendemail').value;
    if ((email.length < 6) || (!emailRegExp.test(email))) {
    	alert('U heeft geen of een ongeldig email van uw collega ingevuld');
    	return false;
    }
    return true;
}

function setSampleText(id, sampletext) {
    if (field = document.getElementById(id)) {
        if (field.value != '') {
            return;
        }
        field.value = sampletext;
        field.className = 'sampletext';
    }
}

function clearSampleText(sender) {
    if (sender.className == 'sampletext') {
        sender.className = '';
        sender.value = '';
    }
}