WordPress Plugin Development: Override Default SMTP

Solution:

Use following code

<?php    
require_once 'phpmailer/PHPMailerAutoload.php';

$mail             = new PHPMailer();

$body             = file_get_contents('contents.html');

$mail->IsSMTP(); // telling the class to use SMTP
$mail->Host       = "mail.yourdomain.com"; // SMTP server
$mail->SMTPDebug  = 2;                     // enables SMTP debug information (for testing)
                                           // 1 = errors and messages
                                           // 2 = messages only
$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";

$mail->MsgHTML($body);

$address = "whoto@otherdomain.com";
$mail->AddAddress($address, "John Doe");

$mail->AddAttachment("images/phpmailer.gif");      // attachment
$mail->AddAttachment("images/phpmailer_mini.gif"); // attachment

if(!$mail->Send()) {
  echo "Mailer Error: " . $mail->ErrorInfo;
} else {
  echo "Message sent!";
}
}

For the variables from the users end, add the above to a shortcode and make insert the smtp details via shortcode perhaps. eg

[sendMail host="mail.yourdomain.com" port="26" username="yourname@yourdomain" password="yourpassword"]