Among many things, Dr. Frank explains how closely voter registrations can be matched with actual voters. From that, miscreants can determine who has voted, and who is likely to never vote. Ballots are then created for that non-voter, who never suspects he’s cast a fraudulent vote.
That’s the curse of motor-voter registration, mailing unrequested ballots, etc. to people who have no interest or likelihood of voting, creating a pool of potential votes to be stolen.
thanks for the link
Early voting, vote by mail, and drop boxes facilitates the fraud.