function isValidEmail(addr){
var invalidChars = '\/\'\\ ";:?!()[]\{\}^|';
for (j=0; j<invalidChars.length; j++) {
if (addr.indexOf(invalidChars.charAt(j),0) > -1) {
//email address contains invalid characters
return false;
}
}
for (j=0; j<addr.length; j++) {
if (addr.charCodeAt(j)>127) {
//email address contains non ascii characters
return false;
}
}
var atPos = addr.indexOf('@',0);
if (atPos == -1) {
//email address must contain an @
return false;
}
if (atPos == 0) {
//email address must not start with @
return false;
}
if (addr.indexOf('@', atPos + 1) > - 1) {
//email address must contain only one @
return false;
}
if (addr.indexOf('.', atPos) == -1) {
//email address must contain a period in the domain name
return false;
}
if (addr.indexOf('@.',0) != -1) {
//period must not immediately follow @ in email address
return false;
}
if (addr.indexOf('.@',0) != -1){
//period must not immediately precede @ in email address
return false;
}
if (addr.indexOf('..',0) != -1) {
//two periods must not be adjacent in email address
return false;
}
var suffix = addr.substring(addr.lastIndexOf('.')+1);
if (suffix.length != 2 && suffix != 'com' && suffix != 'net' && suffix != 'org' && suffix != 'edu' && suffix != 'int' && suffix != 'mil' && suffix != 'gov' & suffix != 'arpa' && suffix != 'biz' && suffix != 'aero' && suffix != 'name' && suffix != 'coop' && suffix != 'info' && suffix != 'pro' && suffix != 'museum') {
//invalid primary domain in email address
return false;
}
return true;
}
function validate_form(){
var frm = document.getElementById('entry_form');
var err ='';
for (i = 0; i < frm.elements.length; i++){	
if(frm.elements[i].className != 'field_mandatory') continue;		
if((frm.elements[i].value=='') 
|| ((frm.elements[i].name == 'user_email') && !isValidEmail(frm.elements[i].value))            
|| (frm.elements[i].name == 'number_in_group' && frm.elements[i].value < 10)){
frm.elements[i].style.borderColor='red';			            
err++;	
continue;
}	
else frm.elements[i].style.borderColor='gray';        
}

if(err) { 
alert('There are errors in your submission form. \nPlease fill in the required fields.');
return false;
}
}