Cannot Telnet to Port 25

Is NOD32 blocking access to port 25 except for well-known email clients (e.g., Outlook, etc.)? I am writing my own email client, just for fun, but cannot connect to my ISP's email server on port 25. I can do this via Outlook. If NOD32 is doing this, how can I add my own program to the list of allowed programs sending data outbound on port 25?

 

Nod32 is not a firewall so i find it hard to believe nod32 is the problem. It should be easy to confirm if you disable nod32 (imon would be the mosts likey reason if nod32 is the problem i think) and try again or use another computer without nod32 installed. If you have some firewall active on your computer i would check that one first or disable the firewall and do another test. If you don't have any kind of firewall installed on your computer and it works fine using outlook or other email clients it sounds like your email client isn't working as supposed to. You could also use a sniffer like wireshark to see if there is any connection attempt at all and if it's working properly using your email client. If you are not familiar with the SMTP protocol you could compare the sniffer trace with a sniffer trace when using outlook or other working email client.

But i think this sounds like a problem with your email client or blocked by a software firewall (if you have any installed) and nod32 is not a firewall.