Found in 11+, may not have been present in Sakai 10. May be related to change of James => SubethaSMTP.
The FROM appears like this: <prvs=8177B7D918email@example.com>
The point of this FROM is to reduce backscatter spam.
The only reasonable solution I can think of is to parse out the "PRVS" in Sakai code. SubethaSMTP seems like a dead project.
SubethaSMTP Javadoc for reference: http://javadox.com/org.subethamail/subethasmtp/3.1.7/org/subethamail/smtp/MessageHandler.html