I'm developing a web application that will send emails on behalf of a logged-in user.

I'm trying to use the new Gmail OAuth protocol announced described here to send these emails through the user's Gmail account (preferably using SMTP rather than IMAP, but I'm easy). However, the sample PHP code gives me a couple of problems.

1. All of the sample code is based on IMAP, not SMTP. Why "support" the SMTP protocol if you're not going to show people how to use it?
2. The sample code gives me a fatal error from an uncaught Zend exception -- it can't find the "INBOX" folder.

Fatal error: Uncaught exception 'Zend_Mail_Storage_Exception' with message 'cannot change folder, maybe it does not exist' in path\to\xoauth-php-samples\Zend\Mail\Storage\Imap.php:467 Stack trace: #0 path\to\xoauth-php-samples\Zend\Mail\Storage\Imap.php(248): Zend_Mail_Storage_Imap->selectFolder('INBOX') #1 path\to\xoauth-php-samples\three-legged.php(184): Zend_Mail_Storage_Imap->__construct(Object(Zend_Mail_Protocol_Imap)) #2 {main} Next exception 'Zend_Mail_Storage_Exception' with message 'cannot select INBOX, is this a valid transport?' in path\to\xoauth-php-samples\Zend\Mail\Storage\Imap.php:254 Stack trace: #0 path\to\xoauth-php-samples\three-legged.php(184): Zend_Mail_Storage_Imap->__construct(Object(Zend_Mail_Protocol_Imap)) #1 {main} in path\to\xoauth-php-samples\Zend\Mail\Storage\Imap.php on line 254

I've verified that I'm getting good OAuth tokens back, I just don't know how to make the actual email transaction happen. This protocol is still rather new, so there's not much unofficial community documentation about it out there, and the official docs are unhelpfully dry stuff about the SMTP RFC. So if anyone can help get this going, I'd greatly appreciate it.

Note: I've already been able to connect to Gmail's SMTP server via SSL and successfully send an email, provided that the user has given my application his/her Gmail username and password. I'd like to avoid this method, because it encourages phishing and security-minded users won't accept it. This question is not about that.