I have 2 computers connected to Wifi router.
One with Windows Vista & second with 2 operating systems: SUSe Linux and Windows 7 64bit on it.
Computer with Vista can connect to SMTP server of my email provider (and any other) using port 25, and can connect to a mail server using
telnet mail.server.com 25 if this port is open.
Computer with dual operating system can (using Linux) do the same.
The same computer, with the same hardware (Wifi card etc.), and using the same WiFi router, cannot however use Port 25 and cannot Telnet into any smtp server.
So the problem is in Windows 7.
I did uninstall all antivirus software and disabled the firewall. The problem is still here.
Is there way how find out which software is blocking this port?