SMTP over Kilostream

[Laxman]

I have two sites 300 miles apart, Site A and Site B. At Site A I have an NT 4.0 Server. On this server I have a package called NT Mail which is a Mail Server Package. Site B is connected to Site A via a Kilostream link with a router at each end. At site B all the workstations have an e-mail client (mainly Outlook Express): these can all collect mail from the Mail Server (POP3) and send mail to the Mail Server (SMTP) without any problem. However Site B can collect mail from the Mail Server (POP3) but when they try to send mail (SMTP) the reply is that the server dropped the connection. (The Kilostream link is a permanently open line between the two sites). All workstations at Site B can PING all workstations at Site A and visa versa. All workstations can TELNET both Routers. All workstations can TELNET the Mail Server at Site A to send mail directly. When I look at the log files for the Mail Server, they say that the other end dropped the connection where as the client software says that the server dropped the connection.<br>
I have been in constant contact with Technical Support for both the routers and the NT Mail package and they both blame each other.<br>
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Can anybody HELP ? Please !!!<br>
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Regards, <br>
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Laxman<br>