checkEmail function

				
//**************************************
// Name: checkEmail function
// Description:Check if a given email address is valid by checking:
 - is the format correct?
 - has the server of the given domain an MX record?
// By: Youry De Winter
//
// Inputs:Example of use:
checkEmail('someone@somewhere.com')
//
// Returns:TRUE when the address is correct format and the domain has an MX record or FALSE when not.
//
// Assumes:If u are using the function on a non-win32 platform, u could use the lighter version, which i included at the bottom.
The reason why I had to make 2 version is simple:
 Win32 does not have the needed modules for using getmxrr() functions in PHP, so I had to re-program the function of PHP itself in order to have a short code.
//
// Side Effects:Using the script on Win32 server platforms makes it run a little bit slower.
//
//This code is copyrighted and has// limited warranties.Please see http://www.Planet-Source-Code.com/vb/scripts/ShowCode.asp?txtCodeId=1867&lngWId=8//for details.//**************************************

//OVERALL COMPATIBLE VERSION
function checkEmail($Email) {
	if ((substr_count(PHP_OS, 'win')) || (substr_count(PHP_OS, 'Win')) || (substr_count(PHP_OS, 'WIN'))) {
		function getmxrr($hostname, &$mxhosts) {
			$mxhosts = array();
			exec('nslookup -type=mx '.$hostname, $result_arr);
			foreach($result_arr as $line) {
				if (preg_match("/.*mail exchanger = (.*)/", $line, $matches)) {
					$mxhosts[] = $matches[1];
				}
			}
			return( count($mxhosts) > 0 );
		}
	}
	if (eregi("^[a-zA-Z0-9_]+@[a-zA-Z0-9\-]+\.[a-zA-Z0-9\-\.]+$]", $Email)) {
		return FALSE;
	}
	list($Username, $Domain) = split("@",$Email);
	if(getmxrr($Domain, $MXHost)) {
		return TRUE;
	} else {
		if(fsockopen($Domain, 25, $errno, $errstr, 30)) {
			return TRUE; 
		} else {
			return FALSE; 
		}
	}
}
//NON WIN32-SERVER COMPATIBLE VERSION
function checkEmail($Email) {
	if (eregi("^[a-zA-Z0-9_]+@[a-zA-Z0-9\-]+\.[a-zA-Z0-9\-\.]+$]", $Email)) {
		return FALSE;
	}
	list($Username, $Domain) = split("@",$Email);
	if(getmxrr($Domain, $MXHost)) {
		return TRUE;
	} else {
		if(fsockopen($Domain, 25, $errno, $errstr, 30)) {
			return TRUE; 
		} else {
			return FALSE; 
		}
	}
}