Haven't been in the US for a while. Are all letters bar-coded?
Have to figure that mail-in ballots would have to have a return address. Driver's licenses should be bar-coded, too correct?
Where I am, in Germany, the registered voters get a letter sent to them with their registration info that they have to take with them to the polling place.
Mail in voting in the US should be done similarly. Registered voters should get a ballot letter sent to them with voter registration info pre-printed on them.
That could be done via the DMV databases in Motor-Voter states. Do the states offering licenses for illegals have any designation on the licenses that the license holder is not a US citizen?