The language in the law says that email providers cannot do something "impeding the transmission of email messages based on content." So, they can probably give you tools to allow/deny emails from addresses you can enter, at least. Given that spam filters blocking fundraising emails from conservative groups is already something discussed among conservatives, it seems at least plausible that making spam filters illegal was actually intended here. I guess we'll find out as soon as someone sues (or the supreme court throws it out).