Not a plugin. I have got gmail working but I’ve gone native to do it.
I replaced the PHPMailer files (wp-includes/class-[phpmailer|smtp|pop].php) with the newer 2.2.1 files that support SSL/TLS connections.
Edited the PHPMailer paramters in wp-include/class.phpmailer.php
public $Host = 'smtp.gmail.com';
public $Port = 465;
public $SMTPSecure = "ssl";
public $SMTPAuth = true;
public $Username = '[username]';
public $Password = '[password]';
Edited wp-include/pluggable.php
require_once ABSPATH . WPINC . '/class.phpmailer.php';
require_once ABSPATH . WPINC . '/class.smtp.php';
[the original files used hyphens e.g. ‘/class-phpmailer.php’
$phpmailer->IsSMTP(); // Use to be $phpmailer->IsMail();
Hope this helps.
-A.