That was the 3rd place I tried the comments field. The other 2 were not good for different reasons. One came out above the masthead and the other messed up the whole form (I think that one was within the existing form tag). Will move it into the form tag, out of the form tag it's in.
I didn't think adding the comments to the checkout page would have anything to do with the email, but that was the only thing I changed on the entire site. What would cause that to happen?