Resolution:
8.2.0 and later EMS server does not allow clients to connect using the SSLv3 protocol. SSLv3 has been deemed a non-secure protocol and newer versions of EMS have removed support for it. Version 5.0.0 .NET client specify uses the SSLv3 protocol when starting the handshake. Later versions since 5.1.5 use TLS instead and can connect successfully.

There are two workarounds:

1). Upgrade the client library to at least version 5.1.5.

2). Revert back EMS server version to 8.1 and prior version which accepts SSLv3. This is not recommended.