New Post: The selected authentication mechanism is not supported

Hi,

I have successfully established a connection to an exchange server but encounter the following exception when attempting a Login:

"The selected authentication mechanism is not supported"

The exchange is a pretty standard TLS, I have tried several different protocols in the ImapClient parameters to no prevail.

extracted code:

_client = new ImapClient(_mailServer, 143 SslProtocols.Tls, false);
_client.Connect();

if (_client.IsConnected)
{
   _client.Login(_login, _password);
}

On execution of _client.Login it throws "The selected authentication mechanism is not supported"?

Any ideas?