When trying to send email, I keep getting a socket #10061 error.
I use the Trap 17 smtp server, related to my own domain, which is mail.vlaanderen-flanders.org.uk.
This seems to be happening regularly lately.
Has anyone got any idea why this could be happening?

Thanks for any support.

Have you submitted a Support Ticket to http://xistosupport.com?

If I remember correctly, #10061 is a connection refused error. However, the title is slightly misleading. The most common cause is the connection never actually being made, most likely due to a firewall or router stopping connections. If you have a firewall or router, make sure they allow traffic to travel freely between your computer and the Internet on ports 25 (SMTP), 110 (POP3) and 143 (IMAP).

The log of my email client then also showed the most common error was "Connection timed out". As for firewall POP3 and smtp port, the ports are all set correctly and I have not changed any firewall settings.
Might be a good idea to raise a ticket, as it starts happening a bit too often.