Blocking a contact prevents that user from contacting you directly. It removes your name from their Contact list. To add a new contact see New Contact
To block a contact:
From the VIA3 Launch Pad select the desired user, choose Tools>Block Contact. You can also select the contact, right click and choose Block Contact.
Your name will be removed form that user's Contact List, and their name will be added to your Blocked Users list located in the Tools > Options > Blocked Users Tab
Blocked users will get a message that you have blocked them when they attempt to add you to their contact list.