I have Windows Server 2008 R2 operating system on the server. The server is not running any Active Directory and is not a part of any Domain. The problem which I am facing is, I cannot run any hMailserver program on the computer. The remote mail client does not connect and hence I tried to use Telnet. While using Telnet is shows that the server is connected to port 25 SMTP successfully but when the telnet is used on client machine, it get disconnected immediately. The hMailerserver log shows that the telnet request was received and responded to, but the connection was disconnected. Therefore If anybody knows why Telnet disconnects while testing Port 25 SMTP then please share some information about the topic. For additional information, all the client machines are running on Windows 7 operating system. Thanks in advance.