I've been getting lots of unwanted messages from a person in my Contact list, what can I do (in ICQ 7)?
If you've just received a message from that person, simply click the Block icon, located on the right of the message window. A warning message will be displayed after you click the button, explaining that the user will be added to your Block List. To confirm click YES.
If you have closed the message the user sent, you can still add him/her to your Block List; right click on the user's name and select Block.
You may also access your Block List by clicking Menu > Contacts > Manage Privacy Lists from the list on the left.