First time Exchange error

[Slider1016]

I'm fairly new to Exchange and one of our users received this error this morning:
"A configuration error in the e-mail system caused the message to bounce between two servers or to be forwarded between two recipients."

My main question is: Would this be on my end or the recipient's? Since I only have one Exchange server, it would seem to be on their end.

 

[Rockn]

Look at the email header on the returned email. It should tell you where the problem is and which server it was bounced from. If you have no forwarding servers I would also check that your server does not have an open relay someone is using for spamming purposes.