In our logs, we find the below:
Router: No messages transferred to example.com (host mx.example.com) via SMTP: The server is not responding. The server may be down or you may be experiencing network problems. Contact your system administrator if this problem persists.
Which is then followed by:
Router: Transferring mail to domain example.com (host mx.example.com [188.8.131.52]) via SMTP Router: Message 12345678 transferred to mx.example.COM for email@example.com via SMTP Router: Transferred 1 messages to example.com (host mx.example.com) via SMTP
Our messages go out normally, but we see this same issue EVERY connection we make. I beleive there is something wrong with my configuration, probably with a timeout, or something similar, but I have not been able to pinpoint it correctly.