I have an Exchange server which has the incoming mail checked by a Barracuda 300 before being distributed by the Exchange server, all this is behind a Draytek router with built in firewall. I have port 25 forwarded to the Barracuda and ports 80, 143, 443 and 3389 fowarded to the Exchange server.
I have a Macbook Pro running Mac Mail using SMTP to send mail, but connot connect to the Exchange server. What's going on? Is it using a different port?