> Thank you. Meanwhile the problem is solved. The reason was a very
> silly one: my Exchange server had no certificates installed.
>
> "Dominick Baier [DevelopMentor]" wrote:
>
>> Hi!
>>
>> glad this was helpful for you.
>>
>> Have you tried to enable tracing for system.net ? does this give you
>> more pointers. Maybe also try a different SslProtocols value.
>>
>> http://www.leastprivilege.com/TracingSystemNet.aspx
>>
>> ---------------------------------------
>> Dominick Baier - DevelopMentor
>> http://www.leastprivilege.com
>>> I order to automate some mail processing I need to access POP3
>>> servers over a secure channel. A couple of MSDN articles recently
>>> written by Dominick Baier was helpful to me when I implemented a
>>> solution in C# with the .NET Framework 2.0. It works fine as far as
>>> I don't try to connect to an MS Exchange 2003 server: In this case,
>>> the connection is terminated by the server. Here is the somewhat
>>> simplified code:
>>>
>>> class CMyPOPClient
>>> {
>>> TcpClient _Channel = null;
>>> NetworkStream _Stream = null;
>>> SslStream _SSLStream = null;
>>> .
>>> .
>>> .
>>> void secureConnect(String strHost, Int32 iPort)
>>> {
>>> .
>>> .
>>> .
>>> _Channel = new TcpClient());
>>> _Channel.Connect(strHost, iPort);
>>> _Stream = _Channel.GetStream();
>>> _SSLStream = new SslStream(
>>> _Channel.GetStream(),
>>> false,
>>> new
>>> RemoteCertificateValidationCallback(validateServerCertificate),
>>> null);
>>> _SSLStream.AuthenticateAsClient( // <== here a
>>> System.Net.Sockets.SocketException
>>> // is thrown with error code
>>> 10053
>>> strHost,
>>> null,
>>> SslProtocols.Tls,
>>> false);
>>> .
>>> .
>>> .
>>> }
>>> .
>>> .
>>> .
>>> }
>>> I should mention that the code is running on a WinXPSP2 PC which is
>>> in
>>> the same Microsoft domain as the Win 2003 Server on which MS
>>> Exchange
>>> is running.
>>> Actually I don't need my code being capable to connect to MS
>>> Exchange 2003 but I don't like to see it fail. Has anybody an idea
>>> what is expected by MS Exchange 2003?
>>>