Error 10061 means that the computer which VPOP3 was trying to connect to (probably at your ISP) refused the connection from the computer running VPOP3.
There are several possibilities that can cause error 10061:
If you see this in a popup window like the one below then it is likely that the VPOP3 status monitor has been unable to connect to the VPOP3 server. In this case you need to
check that VPOP3 is running.
The mail server you are trying to connect to is not running a mail service on the appropriate port. For instance, if you try to connect to an SMTP server on the POP3 port of 110.
The mail server you are trying to connect to is having problems - eg the mail server software is not running
A hardware firewall or router is blocking access to the specified port
A software firewall or 'Internet security software', or virus scanning software is blocking access to the specified port
The VPOP3 connection is set to use a SOCKS proxy, and the SOCKS proxy is unavailable or misconfigured in VPOP3.