I have found a lot of threads on the internet adressing this issue. Unfortunately none of them solved our issue. My customer has 2 EX2010 servers and 2 EX2013 servers running. Al four of them in the same Exchange Organisation. OOO internally works and the replies are received by internal users, but external they are not received. As we are using a mail scanning gateway device we are able to monitor incoming and outgoing messages. It appears that no outgoing OOOR messages are logged. I even doubt that messages are send by the server. Is there somebody who can tell me how to check wether the system tries to send the message in any form of logging? Or maybe someone found a solution for this particular issue.
All suggestions are welcome.