Automatic Maintenance ran this morning, but no icon for me. ... I'm not sure why it needs an email address either.
However, back then when GWX installed itself through Windows Update it was prevented from making outbound connections due to firewall whitelisting. I whitelisted it a few days later, when I had time to investigate what it was exactly, but maybe the initial blocking is linked to why it hasn't appeared today.
I'm way too busy to look into it at the moment, so I'll have a play when I get some time. I've got a couple of months anyway...
PS. I re-read the bit about the email address and you're correct it seems that's if you want confirmation of reservation.
- Win 8 64-bit