Thanks for the quick replies. Please find below the expanded code.
Once again..many thanks
// Validate email field.
if(isset($_REQUEST['email']) && !empty($_REQUEST['email']))
{
$_REQUEST['email'] = trim($_REQUEST['email']);
if(substr_count($_REQUEST['email'],"@") != 1 || stristr($_REQUEST['email']," ") || stristr($_REQUEST['email'],"\\") || stristr($_REQUEST['email'],":")){$errors[] = "Email address is invalid";}else{$exploded_email = explode("@",$_REQUEST['email']);if(empty($exploded_email[0]) || strlen($exploded_email[0]) > 64 || empty($exploded_email[1])){$errors[] = "Email address is invalid";}else{if(substr_count($exploded_email[1],".") == 0){$errors[] = "Email address is invalid";}else{$exploded_domain = explode(".",$exploded_email[1]);if(in_array("",$exploded_domain)){$errors[] = "Email address is invalid";}else{foreach($exploded_domain as $value){if(strlen($value) > 63 || !preg_match('/^[a-z0-9-]+$/i',$value)){$errors[] = "Email address is invalid"; break;}}}}}}
}