how is what different than whos current system?
The US system, using the date of the stamp instead of the arrival date. Neither system is safe from abuse. It's just different.
Mail-in voting is inherently more error prone than voting in person. That's why it's important to make in person voting as accessible as possible. Voting on a Sunday, having plentiful accessible polling stations without significant waiting time surely helps, and is a reason why the share of voting by mail is traditionally way lower here in Germany than in the US. I never had to wait for more than 2 minutes at a polling station here in Germany.
Have a nice new year's eve and guten Rutsch, as we say here.