Less than 1300 cases of frauds in the ENTIRE USA according to the Heritage report you cited... Again regardless of the method for voting, fraud will exist but at an extremely low level. Voters fraud is statistically irrelevant (very,very rare).
It is not what Donald Trump alleged that "millions of people" voted illegally for Hillary Clinton and otherwise he would have won the popular vote.
Vote by mail should be an option available to all eligible voters.