SMTP error: "no route to host"

[rloaderro]

Hello,

I am trying to setup a new Plesk 8.3 server on Cent OS 5. This is what I am up against:

- From what I can tell sendmail works fine
- SMTP however keeps returning "no route to host" errors
- Port 25 is open, however...
- From my home computer I can "telnet some.mail.server 25" no problem
- From the server "telnet some.mail.server 25" returns the same "no route to host" error

What am I missing?