The original post was in the old forum which I thought was now read-only, did I miss something or did you?
Anyway, the above works great from a browser but long wordy URLs with authentication embedded are not possible for the Arduino and Ethernet lib AFAIK. I guess it all comes back to Googles tricky authentication process once again.
I did get this working using Arduino code that talked to an intermediate PHP script on a web server.
Any other ideas on how to make this work with a stand-alone 'Duino and an enet shield?
I think it comes back to the ethernet shield library not being able to handle SSL (https port 443) connections.
edit: If you search the forum for one of my email smtp sketches, it shows how to send to Gmail accounts, but you need a commercial ip address or it will be refused.