[Brooklyn Attitude]

“What would “w no identifying heading” mean?”

IDK, no subject line? It could mean something other than a classification label. Making assumptions is a good way to be disappointed.

[palmer]

There are two possibilities: the entire contents were unclassified and they used secure fax to send it. Sensitive but unclassified or FOUO. The second possibility is that the entire contents are classified. If that is true, there is no "header" that can be removed to make it unclassified. You cannot remove the subject line from a classified email and make it unclassified. Nor anything else witout authority to declassify.

"Making assumptions is a good way to be disappointed."

Likewise ignoring facts.