InvalidSenderError: Unauthorized sender (Google App Engine)

The documentation states:

The From: address can be the email address of a registered administrator (developer) of the application, the current user if signed in with Google Accounts...

This works fine for my app when the current user's Google Account happens to be a Gmail account. It used to work fine for non-Gmail google accounts also but of late I see an error:InvalidSenderError: Unauthorized sender f开发者_如何学Cor non-Gmail google accounts. Am I missing any recent changes to the implementation?

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Since May 10 (with the 1.5.0 SDK release) the additional restrictions where added:

We have added two restrictions to the Mail API to improve the reliability of the service for all application. Emails must be sent from email accounts managed by Google (either Gmail or a domain signed up for Google Apps).

It seems the documentation does not reflect this change yet.