Issue emails suddenly stopped flowing to exchange 2019 server on 12/31

We have a local exchange server as well as a local spam titan instance. I am seeing email flow to the spam titan and it looks to be releasing to go to the exchange server. everything was working prior to the break and can confirm nothing has been changed since. I have checked the hard drive space and that appears fine. I have checked the dns records as well as the ip address none of that has changed. I am looking for someone who can help troubleshoot and get mail flowing as soon as possible as our organization is down at the moment