[Bro] Internal hostname in mail.log

[Will]

Hi All,

Can anyone help me determine which broctl script/postprocessor (I'm
assuming) is adding an internal hostname (user.host.com) to mail.log.

cat mail.log:
>  2011-05-02-11:43:05 HTTP_IncorrectFileType (L) 10.0.0.1 = user.host.com
  <bro> application/x-dosexec http://www[.]bad[.]com/PrintPeer[.]dat

I would like to add internal hostnames to some other alerts and would
like to avoid re-creating the wheel.

Thanks in advance for any help!

Will