In order to avoid endless mail looping on our server, which can bog it down and ultimately may cause it to go down, you will be unable to forward mail as follows:

box1–>box2–>outside address

This scenario will only send the mail to the server location for box2; it won’t send the mail to the outside address. If you want box 1 to go to the outside address, you’ll need to forward it there directly, instead of sending it to box2 first and from there having it go to the outside address.