Вы смотрели пример smtp на их сайте? Смотрите здесь
Если я не скучаю по тебе, это выглядит очень прямо.
$mail = new PHPMailer();
$body = "message";
$mail->IsSMTP(); // telling the class to use SMTP
$mail->Host = "mail.yourdomain.com"; // SMTP server
$mail->SMTPAuth = true; // enable SMTP authentication
$mail->Host = "mail.yourdomain.com"; // sets the SMTP server
$mail->Port = 26; // set the SMTP port for the GMAIL server
$mail->Username = "yourname@yourdomain"; // SMTP account username
$mail->Password = "yourpassword"; // SMTP account password
$mail->SetFrom('name@yourdomain.com', 'First Last');
$mail->AddReplyTo("name@yourdomain.com","First Last");
$mail->Subject = "PHPMailer Test Subject via smtp, basic with authentication";
$mail->AltBody = "To view the message, please use an HTML compatible email viewer!"; // optional, comment out and test
$mail->MsgHTML($body);
$mail->AddAddress("whoto@otherdomain.com", "John Doe");
if(!$mail->Send()) {
echo "Mailer Error: " . $mail->ErrorInfo;
} else {
echo "Message sent!";
}