<?php

/**

 * Sends e-mail via SMTP.

 * @param string Source address

 * @param string Destination address

 * @param string Subject

 * @param string Message body

 * @param string Additional headers

 * @return bool

 */

function smtp_mail($from, $to, $subject, $body, $headers = '')

{

	list($domain) = array_reverse(explode('@', $to));

	// look up MX record for $domain

	$record = dns_get_record($domain, DNS_MX);

	if ( !isset($record[0]['target']) )

		// failed to get target server

		return false;

	// open socket

	$sock = fsockopen($record[0]['target'], 25, $errno, $errstr, 5);

	if ( !$sock )

		// failed to open socket

		return false;

	try

	{

		// wait for 220

		if ( _smtp_get_response($sock) !== 220 )

			throw new Exception("Expected 220");

		// HELO

		// get server's FQDN

		$hostname = gethostname();

		if ( strpos($hostname, '.') === false )

		{

			$hostname .= '.' . trim(`dnsdomainname`);

		}

		fputs($sock, "HELO $hostname\r\n");

		if ( _smtp_get_response($sock) !== 250 )

			throw new Exception("Expected 250");

		// from

		fputs($sock, "MAIL FROM: <$from>\r\n");

		if ( _smtp_get_response($sock) !== 250 )

			throw new Exception("Expected 250");

		// to

		fputs($sock, "RCPT TO: <$to>\r\n");

		if ( _smtp_get_response($sock) !== 250 )

			throw new Exception("Expected 250");

		// data

		fputs($sock, "DATA\r\n");

		if ( !in_array(_smtp_get_response($sock), array(354, 250)) )

			throw new Exception("Expected 250 or 354");

		// send headers

		$full_headers = "Subject: $subject\r\n";

		$full_headers .= "From: <$from>\r\n";

		if ( !strstr($headers, "To: ") )

			$full_headers .= "To: <$to>\r\n";

		if ( !empty($headers) )

			$full_headers .= trim(str_replace("\n", "\r\n", str_replace("\r\n", "\n", $headers))) . "\r\n";

		$full_headers .= "\r\n";

		fputs($sock, $full_headers);

		// send body

		$body = str_replace("\n", "\r\n", str_replace("\r\n", "\n", $body));

		fputs($sock, $body);

		// send end marker

		fputs($sock, "\r\n.\r\n");

		if ( _smtp_get_response($sock) !== 250 )

			throw new Exception("Expected 250");

		// end session

		fputs($sock, "QUIT\r\n");

		if ( _smtp_get_response($sock) !== 221 )

			throw new Exception("Expected 221");

		fclose($sock);

	} catch ( Exception $e )

	{

		fputs($sock, "QUIT\r\n");

		_smtp_get_response($sock);

		fclose($sock);

		return false;

	}

	return true;

}

function _smtp_get_response($sock)

{

	while ( !feof($sock) && ($line = fgets($sock, 8192)) )

	{

		if ( preg_match('/^([0-9]+)(\s.+)?$/', $line, $match) )

		{

			return intval($match[1]);

		}

	}

	return false;

}

// smtp_mail('plates@csh.rit.edu', 'plates@csh.rit.edu', 'Test e-mail', 'Testing', 'From: Plates <plates@csh.rit.edu>');