This blog post explains the meaning of the following error condition:
SocketError: WSAECONNABORTED An established connection was aborted by the software in your host machine.
Error sending on socket
Failed when sending email body
(More information about WSAECONNABORTED)
If you are sending a large email, and the SMTP server disconnects while the body of the email is being transmitted by your application, you may see this error. While the client app is still sending, the Windows OS (WinSock) shuts down the socket connection — thus you see the somewhat misleading error "An established connection was aborted by the software in your host machine.". The "software in your host machine" is WinSock itself. (In some cases it could be caused by anti-virus software.)
The solution is to determine why the SMTP server decided to disconnect prior to receiving the complete email.