Block and unblock messages
To block messages, connect to the instant messaging service, and select
Conversations > IM contacts; or join or start a conversation. Scroll to
the contact from whom you want to block incoming messages, and
select Options > Block contact > OK.
To unblock the messages, connect to the instant messaging service, and
select Blocked list. Scroll to the contact from whom you want to unblock
the messages, and select Unblock.