With smime configured correctly (incoming smime signed emails have verified good signatures, outgoing signed emails are blank. The outgoing email record looks like this:
Content-Type: multipart/mixed; boundary="----------=_1506007716-21211-10"
MIME-Version: 1.0
Precedence: bulk
X-RT-Original-Encoding: utf-8
Content-Length: 0
X-RT-Original-Encoding: iso-8859-1
Content-Length: 0
Content-Transfer-Encoding: base64
Content-Disposition: inline
Content-Type: application/x-rt-original-message
Content-Length: 894
download
The original message according to RT looks like this
X-Mailer: MIME-tools 5.509 (Entity 5.509)
MIME-Version: 1.0
Content-Transfer-Encoding: binary
X-RT-Interface: Web
Content-Type: text/plain; charset="utf-8"
X-RT-Original-Encoding: utf-8
RT-Send-CC:
X-RT-Encrypt: 0
X-RT-Sign: 1
Content-Length: 217
And then there is content here.