Convert this mod for 3.6 compatibility?

[kontrabass]

This mod, originally posted (unofficially) by ChurchMedia, works great in 3.5. It sends out a thank-you email to new paid subscribers at the time of subscription build. In 3.6, it still works but the name of the subscription remains blank in the email: something's wrong with $sub[title] Anyone know what the syntax is for the subscription title in 3.6?

Here it is:

<?xml version="1.0" encoding="ISO-8859-1"?>

<product productid="emailsubscriber" active="1">
	<title>Email Subscriber</title>
	<description>Emails a new or expired subscriber and the Admin</description>
	<version>1.00</version>
	<codes>
	</codes>
	<templates>
	</templates>
	<plugins>
		<plugin active="1">
			<title>Email Subscription</title>
			<hookname>paidsub_build</hookname>
			<phpcode>
vbmail_start();
$adminemail = "admin@yoursite.com";
$subsubject = "$user[username] - $sub[title]";
$adminmessage = "$user[username] has subscribed to $sub[title].\n\n Member Profile: http://www.yoursite.com/forum/member.php?u=$user[userid]";
vbmail($adminemail, $subsubject, $adminmessage);
vbmail_end();

vbmail_start();
$useremail = "$user[email]";
$subsubject = "$sub[title]";
$adminmessage = "Dear $user[username], \n\nThank you for your donation for a $sub[title]! Thank you message here... blah blah blah";
vbmail($useremail, $subsubject, $adminmessage);
vbmail_end();

</phpcode>
		</plugin>
		
	</plugins>
	<phrases>
	</phrases>
	<options>
		<settinggroup>
		</settinggroup>
	</options>
</product>