Unless you've come up with some new unknown method of inviting people and having them join, you are scamming a lot of people out of some bitcoins.

1. Sending the share to someone without gives them the email, but I think they only distribute them so many at a time.

2. You receive the email, and get notified about looking at the share (whatever it is you commented on, etc) and click the link.

3. They get sent to a page that says they are over capacity and a button to keep you notifed.

AFAIK there are no more invites being allowed, so I'd be weary.