I have a CES where quite often the mails gets rejected by the CES and so much to the point where we need to bypass the CES.
I see this on the mail client:
Remote Server returned '550 #5.7.1 Your access to submit messages to this e-mail system has been rejected.
It's not all mails but a lot of them and this started after an upgrade of the Exchange server.
I got the system_logs and error_logs but there is noting there which explains the issue.
What logs from the CES do I need to get to see why the get rejected and where?