My problem with vote-by-mail is that they have to confirm that your signature is the same... and mine is not. I have been voting by mail but I don't know if they count my vote.
At least in my county, although I expect most have something similar, you can check the status of your ballot online. If that's not available, my local officials have always been more than helpful over the phone.
I've actually been notified by Oregon when my signature has been different enough from what's on file with them. Happened once out of like 10 times I've voted out here. The mailing confirmed my prior vote counted and asked me to sign a piece of paper with a new signature so they could have an updated signature on file. Was pretty seamless.