We have a user outside of our organization / exchange environment that when we send her a new email with an image embedded in the email, it gets stripped. The marker is still there, but the actual image is gone.
So if I send her a new email with an embedded image she get's a " [cid:image001.jpg@01D055c5.69ACE080]" link where the image use to be.
Now, if I reply to an email that she sent me and I embed an image in that reply, it goes through fine.
I receive embedded images from her without issue.
She does not have this problem with anyone else and neither do we.
I'm not exactly sure on her outlook version but it's at least outlook 2010.