Although this Google document describes a simple way for a GAE app to send a message to a Talk/Chat user, apparently this feature has been discontinued. Is there another method for a GAE app to send a message to a Talk/Chat user?
As an aside: for SMS'es from real phones sent to my Google Voice number, each SMS received is also received as an email in my Gmail account. And the sender of the email is [email protected], where 1888... is my GV number and 1999... is the sender of the SMS. I can reply an SMS to the sender by simply sending mail to this email address. This email address does not expire, ie I can still send SMS'es using this months later.
Is there a similar way to deliver messages to Talk/Chat by sending to a specially formatted email address?