Probably not, according to the Heritage Foundation’s data. The think tank compiles a database of reported instances of voter fraud or election fraud. It lists 1,277 “proven instances of voter fraud” in the 50 states over decades, dating back to 1979. The database caveats that it does not purport to be an “exhaustive or comprehensive list.” But given its repeatedly expressed concerns about voter fraud in general and mail ballot fraud in particular, it seems unlikely it would leave out many reported instances of that kind of fraud.
The database includes many categories of the types of voter fraud involved: Registration fraud, voter impersonation fraud, illegal “assistance” at the polls, etc. But only some are relevant to the specific concerns about mailed ballots: “Fraudulent use of absentee ballots” and “vote buying.”
If widespread use of mail ballots truly did engender fraud, one would expect that the instance of such kinds of fraud would be lower in the 16 states that strictly regulated absentee balloting as opposed to the 28 states, which allowed anyone to vote absentee (“no excuse” absentee voting states) or the five states that automatically mailed ballots to all voters for them to mail back or drop off (“vote-by-mail” states).
Instead, the opposite is true. An examination of the Heritage Foundation database for the period 2000-2020 shows that reported instances of such fraud per capita are actually higher in “strict” states than either “no excuse” states or complete “vote by mail” states.
For these types of fraud, within the 29 “no-excuse” absentee states, there was one reported fraud case for every 2.4 million persons. This compared favorably to one such case for every 1.6 million persons in “vote by mail” states, and even more favorably than the strict states, with one fraud case for every 740,000 persons. Although mail ballot fraud was by no means frequent in any of the states, it was actually more common in the states that took the stricter, more Trump-favored approach.
It is true that pure vote-by-mail states had a slightly higher rate than no-excuse states, potentially aiding the argument that more mail ballots leads to more fraud. But the vote-by-mail rate was only 1.5 times that of the no-excuse rate, while the strict states’ rate was twice that of vote-by-mail, and over three times that of no-excuse states. This doesn’t seem consistent with the notion that liberalizing mail voting increases fraud.