Mail voting is incredibly weak and incredibly stupid.
There is no way to verify that the person voting is the correct person and he is not forced in any way.
Your paper trail is completly useless if you cannot prove it has a proper origin.
Voting in secrecy in a nice voting booth using a simple straightforward ballot is a beautifull system. It is simple enough that you can not only explain it to a ten year old, the ten year old can actually go see for him self and verify proper procedures are followed.
Yet again and again people try to fuck it up with mail or electronic voting schemes.