We have really struggled to resolve this issue that has been going on for a while now. We get this error intermittently when sending to various outside domains A configuration error in the e-mail system caused the message to bounce between two servers or to be forwarded between two recipients. Contact your administrator. <ourservername.ourdomainname.com #5.3.5> It doesn't happen on all our e-mails, so it makes it really hard to troubleshoot. We only have one Exchange Server (Ex2003 SP2 Std Ed). We have tried removing the SMTP Connector as we read that is optional, but that didn't help. Any ideas would be appreciated.

It seems two user have forward address to each other. you should remove these forwards (at least one of them)

No, that is not the issue because it doesn't just happen with one person from our company, but several different people.