MSCRM 2013 EMAIL Error: 26090 Unable to read data from the transport connection

Question

Hello Everyone,

I am getting below mentioned error.
The functionality was up and running for years suddenly I started getting this error.

Event Viewer Logs:

26090 - An error occurred while opening mailbox abc.xyz@Kimmy .ca. System.Net.WebException: The underlying connection was closed: An unexpected error occurred on a send. ---> System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host. ---> System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host

at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size)

--- End of inner exception stack trace ---

at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size)

at System.Net.FixedSizeReader.ReadPacket(Byte[] buffer, Int32 offset, Int32 count)

at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest)

at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyn

Email Router tool:

Incoming Status: Failure - The underlying connection was closed: An unexpected error occurred on a send. Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host. An existing connection was forcibly closed by the remote host

Can anyone suggest me the root cause or suggest me the solution for this issue.
Thanks in advance