function writeTag() {
  var u = 'dltestingjp';
  var d = 'exova';
  var tld = 'com';
  var a = u + '@' + d + '.' + tld;
  document.write('<br />Email:&nbsp;&nbsp;');
  document.write('<a href="mailto:');
  document.write(a);
  document.write('">');
  document.write(a);
  document.write('</a>');
}
writeTag();