I figured this would be the best place to get an answer.
I'm having a disagreement with my local post office.
I tried to mail a camera lithium battery. They said I couldn't. I've even asked two clerks on two separate occasions and they both say the same thing - you can mail a battery attached to the item but not the battery alone.
I say they are far more likely to overheat while attached to the item than just the battery by itself.
Who's right?