mike,
Increditmail used to use web beacons.
Not sure if they still do.
Would that have any effect on the problem?
My guess would be "no", because Anita reported that the messages come through ok when there's no side border. I can't think of a reason the beacon would be missing or different without the border.
That said, if the Incredimail user has the option to turn off delivery tracking, or whatever they call it, that wouldn't hurt. I don't know though if Incredimail users are informed about whether their messages are read by the recipient - it might not be an optional feature.
Shal
Shal Farley