Why is my new received email diplaying as already read instead of being bold until I open and read?

I have this same problem. I was just coming here to post about it, but apparently this original poster isn't getting any responses.

Once my account is open, then the new emails come through in bold like they should.

I also noticed that in the g-mail account emails load in bold.

It's annoying enough that if mozilla does not fix it soon I'm leaving them.