If you're mailing in a paper ballot,the only machine they're using is one that identifies the boxes you filled in - like those use for stardardized testing.
The voting machines that get hacked are ones with digitized platforms - touch screens and all.
What your actual people do with your paper ballot is the only concern you should have. I could be wrong, but I believe this is the case.
My state doesn't have voting machines, just the mechanical ballot counters as described above. We still use paper ballots.