X-Spam-Status: No, score= X-Spam-Score: X-Spam-Bar: X-Spam-Flag: NO
X-Spam-Bar is not a standard SA header. Someone asked about this a few weeks ago, but I don't recall the result of the thread. My best guess at the moment is that whatever integration tool you are using is calling SA and then putting its own results into the mail message after looking at what SA said. In this canse, maybe either it is failing to call SA or for come reason SA itself is failing on these messages, so the tool ends up sticking in empty headers.
Tell us what OS you are using and what the mail tools are that you are using.
Loren