$from = 'свое значение';

function send_mail($recipient, $subject, $body, $from = '')
{
include '/plugins/class.phpmailer.php';

$mail = new PHPMailer();

if (defined('SMTP_MAIL') && SMTP_MAIL && SMTP_HOST && SMTP_LOGIN && SMTP_PASSWORD)
{
$mail->IsSMTP(); // telling the class to use SMTP
$mail->Host = SMTP_HOST; // SMTP server
$mail->SMTPDebug = MOD_DEVELOPER ? 1 : 0; // enables SMTP debug information (for testing)
// 1 = errors and messages
// 2 = messages only
$mail->SMTPAuth = true; // enable SMTP authentication
if (SMTP_PORT)
{
$mail->Port = SMTP_PORT; // set the SMTP port for the GMAIL server
}
$mail->Username = SMTP_LOGIN; // SMTP account username
$mail->Password = SMTP_PASSWORD; // SMTP account password
}

$mail->SetFrom($from ? $from : EMAIL_CONFIG, TITLE);
$mail->Subject = $subject;
$mail->MsgHTML($body);

if (is_array($recipient))
{
foreach ($recipient as $to)
{
$mail->AddAddress($to);
}
}
elseif (strpos($recipient, ',') !== false)
{
$recipients = explode(',', $recipient);
foreach ($recipients as $r)
{
$mail->AddAddress(trim($r));
}
}
else
{
$mail->AddAddress($recipient);
}
$mailssend = $mail->Send();

return $mailssend;
}

send_mail($recipient, $subject, $body, $from);
?>

$curl_result = htmlspecialchars_decode(urldecode($curl_result));
else $curl_result = "/"; // вместо "/" лучше указать адрес страницы, говорящей об ошибке.
curl_close($ch);

$this->result["redirect"] = $curl_result;