Can I have a form with email validation?

 
As of now, Pressero forms do not offer any validation. However, as a possible workaround, there is a free 3rd party tool available called formsmarts.com. They offer various validations. You could try them. Please check the link below for more information.
 
 https://aleyantprintsoftware.com/2012/12/14/using-a-form-in-your-web-to-print-storefronts-to-generate-sales-leads/