In my state, (AZ) mail in ballots had to be formerly requested in writing with a valid phone number and 3d barcode of your driver's license or equivalent ID. Dropping off a ballot or voting in the traditional fashion also required a phone number and ID with the additional check of a living, breathing person comparing the picture on the ID to your smiling face.
There were grumblings yesterday about voter fraud in AZ, (Mostly by people who don't understand the huge differences between the Latino population here and the one in Florida) but we did it right this time.