I followed the "Perfect Hardy Heron Ubuntu Server" step by step, but I am still unable to access my remote SMTP server from my desktop (i.e., I cannot send a test email using Thunderbird.)
The server resides on a VPS host, and I can send mail from the command line. However, I cannot connect to the SMTP server via Thunderbird, not can I telnet to port 25.
How do I:
- Test if port 25 is open?
- Open it safely if it isn't?
- Change the port if my local ISP is blocking it?