I just signed my friend up for glitch via the new facebook stuff which seems to work great, however (and not that I'm planning on unsubscribing) I noticed that it's missing an unsubscribe link at the bottom which I think is required (and is generally a good practice):
The email read:
Since you two know each other, we've added you as each others' buddies
in the game. Your friend's Glitch name is Foo. Maybe you can help
them to find their way around the world a bit?
Thanks for helping to grow the Glitch community by inviting your
friends!
This email was sent by Tiny Speck. If you didn't request it, maybe you
should have?