I'm working on a UCCX 8.5.1 install and I've configured agent email and am receiving emails fine. However, when I reply to emails from CAD the emails are never getting to their destination. In CSD the emails show as sent. I can telnet to the SMTP server on the SMTP port and can send an email using telnet commands fine from the UCCX server subnet so that all looks ok. The Exchange 2007 admin has assured me that the SMTP handler is configured as per the CAD install guide.
There is a firewall between the UCCX and the Exchange server and port 25 is open between them however, port 25 isn't open from the desktops to the Exchange server. From my understanding though it's the EEM service on the UCCX server that's doing the sending isn't it? I can't seem to see very much in the logs. The CAD logs seem to say the email is sent. The debug logs from the EEM service don't really seem to show a great deal from what I can make of them when the agent replies to the email.