My accounts team use an accounting package that generate emails and send via SMTP.
The software was configured with the IP address of our exchange 2003 server.
This server has been removed and replaced with a new exchange 2010 server.
The software's config was updated with the new IP of the new server.
Since the change, recipients are not receiving emails generated.
The application's support team have confirmed emails sent by the software have left their software and the SMTP is replying with a success message and will not provide us any more assistance as they claim this is a fault with our server.
We have other applications that send emails, they are all working without issue.
Where do I begin to troubleshoot this issue, I would agree with their support team that it is an issue with our Exchange 2010 server but I do not know what logs to read, or settings to change.
Any help would be greatly appreciated.