100% Vote-By-Mail is the answer to several important questions about American elections...
Election security... Vote-By-Mail inherently leaves a paper trail that is easy to audit. The Vote-By-Mail ballots can be counted twice, by unrelated machines and unrelated staff, and if the results are identical, the election is pretty secure. Vote-By-Mail is also inherently inaccessible from the internet.
The push to make election day a federal holiday... Vote-By-Mail allows voters to make their decisions and vote from the convenience of their own homes at a time of their own choosing, so there is no necessity of the expense and disruption of an Election Day holiday.
Accessibility... Vote-By-Mail provides optimum accessibility for the disabled and others who have trouble traveling, walking, reading, etc.
Cost... The equipment to scan Vote-By-Mail ballots is much less expensive than voting machines. And far fewer people are required to staff a Vote-By-Mail system.
Convenience... There is no waiting in line to vote with Vote-By-Mail. And any technical issues (which are much less likely with Vote-By-Mail) do not cause delays or inconvenience to voters.
Voter ID issues... With Vote-By-Mail, there is the possibility of informing a voter of a discrepancy and for them to resolve it before voting is finalized.
http://www.ncsl.org/research/elections-and-campaigns/all-mail-elections.aspx
https://postalnews.com/blog/2016/04/29/senator-calls-for-national-vote-by-mail-to-fight-back-against-new-barriers-to-voting/
https://etvnews.com/voting-by-mail-is-the-safe-secure-and-easy-way-to-vote-this-election-day/