function sendForm()
{
 	var username, email, comments;
	username = document.getElementById('Username').value;
	email = document.getElementById('UserMail').value;  
    comments = document.getElementById('Comments').value;
	if (username.length==0 || comments.length==0 || email.length==0) 
	{
		alert('Συμπληρώστε σωστά την φόρμα!');
	}
	else
	{	
		var xmlHttp;
		try {
		// Firefox, Opera 8.0+, Safari
		xmlHttp=new XMLHttpRequest();
		} catch (e) {
		// Internet Explorer
		try {
		xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
		} catch (e) {
		try {
		xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
		} catch (e) {
		alert("Ο browser σας δεν υποστηρίζει AJAX!");
		return false;
		}
		}
		}
		xmlHttp.onreadystatechange=function()
		{
		if(xmlHttp.readyState==4)
		{
		aaa = xmlHttp.responseText;
		 
							if (aaa=='ok')
							{
								alert('Το μήνυμα σας εστάλη με επιτυχία.');
							}    //end if - email added
							else
							{
								alert('Το μήνυμα σας εστάλη με επιτυχία.');
							} //end else - referrer not recognised
		}
		}
		xmlHttp.open("GET","sendcontactform.php?&username=" + username + "&comments=" + comments + "&email=" + email, true);
		xmlHttp.send(null);
	} //end else  
} //end function