PHP SMTP Authentication: send an email through an authenticated SMTP server

Author: Matthew R. Miller, http://www.bytemycode.com/snippets/snippet/223/

<?php
function mymail($to,$subject,$message,$headers)
{
// set as global variable
global $GLOBAL;
// get From address
if ( preg_match("/From:.*?[A-Za-z0-9\._%-]+\@[A-Za-z0-9\._%-]+.*/", $headers, $froms) ) {
preg_match("/[A-Za-z0-9\._%-]+\@[A-Za-z0-9\._%-]+/", $froms[0], $fromarr);
$from = $fromarr[0];
}
// Open an SMTP connection
$cp = fsockopen ($GLOBAL["SMTP_SERVER"], $GLOBAL["SMTP_PORT"], &$errno, &$errstr, 1);
if (!$cp)
return "Failed to even make a connection";
$res=fgets($cp,256);
if(substr($res,0,3) != "220") return "Failed to connect";
// Say hello...
fputs($cp, "HELO ".$GLOBAL["SMTP_SERVER"]."\r\n");
$res=fgets($cp,256);
if(substr($res,0,3) != "250") return "Failed to Introduce";
// perform authentication
fputs($cp, "auth login\r\n");
$res=fgets($cp,256);
if(substr($res,0,3) != "334") return "Failed to Initiate Authentication";
fputs($cp, base64_encode($GLOBAL["SMTP_USERNAME"])."\r\n");
$res=fgets($cp,256);
if(substr($res,0,3) != "334") return "Failed to Provide Username for Authentication";
fputs($cp, base64_encode($GLOBAL["SMTP_PASSWORD"])."\r\n");
$res=fgets($cp,256);
if(substr($res,0,3) != "235") return "Failed to Authenticate";
// Mail from...
fputs($cp, "MAIL FROM: <$from>\r\n");
$res=fgets($cp,256);
if(substr($res,0,3) != "250") return "MAIL FROM failed";
// Rcpt to...
fputs($cp, "RCPT TO: <$to>\r\n");
$res=fgets($cp,256);
if(substr($res,0,3) != "250") return "RCPT TO failed";
// Data...
fputs($cp, "DATA\r\n");
$res=fgets($cp,256);
if(substr($res,0,3) != "354") return "DATA failed";
// Send To:, From:, Subject:, other headers, blank line, message, and finish
// with a period on its own line (for end of message)
fputs($cp, "To: $to\r\nFrom: $from\r\nSubject: $subject\r\n$headers\r\n\r\n$message\r\n.\r\n");
$res=fgets($cp,256);
if(substr($res,0,3) != "250") return "Message Body Failed";
// ...And time to quit...
fputs($cp,"QUIT\r\n");
$res=fgets($cp,256);
if(substr($res,0,3) != "221") return "QUIT failed";
return true;
}
?>