I get "Invalid email address" for my email so they are applying some sort of aggressive filtering on their email acceptance anyways which IMO is a really bad sign they are building an email list they want to profit from.

If you look at their pricing model, which is 4 free... sign up for paid plan to get more then the aggressive email validation makes a bit more sense. I'm not connected to them in any way, just trying to give the benefit of the doubt.