My son has a mailbox under my doman - let's say son@mydomain.com and I have one of course me@mydomain.com, which is a catchall.    I have recently attempted to set it up so everything  for mydomain.com goes to myotherdomain.com

The result is that everything *except* son@mydomain.com gets forwarded to myotherdomain.com, while my son's mail is trapped in his own mailbox and stays there.    This does not appear to match what the feature says it will do?