Edie Goldenberg studied mail-in balloting as part of a National Academy of Public Administration working group. The group found that “voting by mail is rarely subject to fraud, does not give an advantage to one political party over another and can in fact inspire public confidence in the voting process.”
The full article by The Conversation on the safety and reliability of mail-in voting is available here.
Goldenberg's synopsis of the working group's findings are available via The Conversation here.
The Election 2020 National Academy of Public Administration working group action plan is available here.