This is a better guide on how to change the settings. It shows the screens you need. Obviously yo use the VM settings and not the ones on the screen
But there is a trick. Tick the box which says "server requires a secure connection SSL" before changing the port number to 465 for SMTP and 993/995 for IMAP/POP depending on which e-mail protocol you are using. Only you know that. And if you don't follow the trick it goes wrong.
If you are comfortable with WLM for the moment make these changes. I did . It all works. When you change PC switch to a client like Thunderbird which automatically sets itself up with the right VM mail settings.
As a Very Insightful Person, I'm here to share my knowledge. I don't work for Virgin Media.