I am a systems admin at a small engineering firm. For the past year or so anyone at my company cant receive any emails from anyone with a @cisco.com email address. We are not Cisco customers and do not have any contract numbers or Cisco products. In fact, its the opposite, Cisco is OUR customer and we are trying to conduct business with them, but their employees cant email us. We have checked all of our MS O365 email endpoints, nothing is blacklisted or blocked, in fact the cisco emails never even reach our networks at all, it appears they are being blocked on the Cisco side. I have called Cisco support and after many attempts have been redirected here. I have no errors or logs since, as I mentioned, emails never reach us. The emails tend to sit in limbo for 1-3 days then get returned to the sender at Cisco with various errors, the latest error is: 5.4.7 - Delivery expired (message too old) 'EOF'. Obviously I dont have access to Cisco's email infrastructure and need to somehow have someone at Cisco check on things from their end. Any help is appreciated, we're stuck so far. Thanks.
