Original-Message-ID ?????

I have send a message including a reception confirmation. I received the reception confirmation wich indicate a strange information. It is written,
Final recipient : "me@myfai"
Original message ID : "xxxxxxx.xxx.camel@yyubuntu"
where "me@myfai" is my adress
"xxxx" a serial of numbers
"yy" my pc identification.
I'm worried about that: does it mean my messages contain personnal and confidential information readable by recipients ? Is there any security failure ?