Form always redirects, even when no email entered

Great plugin, thanks.

I am using it to redirect users to a particular page after submitting their email address. However, even when no email address is entered, clicking the submit button still causes the redirect.

I assumed it is only supposed to redirect when a valid email address is entered, is that not the case? If so, is there some setting to cause the correct behaviour?

thanks.

https://wordpress.org/plugins/email-pick-up/