This error code means that you lost your connection. You will get this error if the remote side disconnects (whether its forcibly-- by pulling their ethernet cable out of the computer), or gracefully (the software closing the connection). This may or not be a true error situation. If the remote side closed the connection, then it is not truly an error; it's just a status indication. But if they pulled the ethernet cable out of the computer, then it really is an error; but the results are the same. The connection was lost.
Error #103 means eMail Verifier was unable to resolve the address that was specified. A prime example of this would be a mistyped IP address, or a domain name of an unknown or unreachable host.
Error 101 and 104 don't exist. Error 105 doesn't apply here. Error 106 is a status error, it should never happen (connection closed when writing to it). Error 107 is port invalid. Finally 108 means Out of memory.