Emails Forwarded to MYOB Intray via outlook rules being rejected

I have tried to set up rules in our outlook email to automatically forward our incoming invoices to our MYOB intay are being rejected. I have tried both the "forward to" and the "redirect to" rule options.

I get an email telling me it was "undeliverable"

This is what the email says 

"Delivery has failed to these recipients or groups:

........email address......
Your message wasn't delivered because the recipient's email provider rejected it."

Then it has the "diagnostic informaton for administrators"

Please help