Get Notified Form Service

Which is the best paid landing page plugin-service for an upcoming product to let users enter their email address to get notified when the product launches ?

1. I don't want to end up creating a module just for that
2. I need the (embed) code not to allow random email ids to prevent fraud.

The only ones I can think of are Google Forms (free) where I can enforce email login and wufoo (paid).

Any other better suggestions ? WordPress ...