The bounce back is in the message below.
This started happening after I reconfigured the network on the server using the Broadcom utility. It was using a single NIC before, and I created a team using both adapters. I then reconfigured the virtual NIC for the team to have the same TCPIP settings as the server had previously.
So esentially, to the OS, i changed the network adapter.
This is an automatically generated Delivery Status Notification.
THIS IS A WARNING MESSAGE ONLY.
YOU DO NOT NEED TO RESEND YOUR MESSAGE.
Delivery to the following recipients has been delayed.