What happened to the plain old Federal Election Postcards you could use to register and/or request ballots? The states were required to accept them. I was stationed overseas from 1990-2004 and used these every federal election. Never had any problems getting an absentee ballot from my state (AK).
I did have a problem in 2006.
My Alaska ballots never arrived.
It would not have made a difference, as my candidates won.
But, my vote was not among them.