Voter files being public data depends on which state you're talking about -- you're looking at ~50 different sets of laws and regulations. Some states restrict

Voter files being public data depends on which state you're talking about -- you're looking at ~50 different sets of laws and regulations. Some states restrict access to only political parties using it for political uses and prohibit distribution to non-parties/candidates. Some states (Florida, for example) will let anyone just apply to get it. To your latter question, some states, like California, do include email addresses on their voter file, but the coverage tends to be poor. You can probably assume that, if you're a registered voter in the United States, you're on this dataset, as is your age, gender, party affiliation if applicable, and race/ethnicity info if your state collects that, as well as modeled information projecting things like party support, race, age, and likelihood to turnout.