Block or unblock messages
When you are in a conversation and want to block messages, select
Options > Block contact. A confirmation query is shown, select OK to
block messages from this contact.
To block messages from a specific contact in your contacts list, scroll to
the contact in Conversations, Online or Offline and select Options >
Block contact > OK.
To unblock a contact, in the IM main menu select Options > Blocked
list. Scroll to the contact you want to unblock and select Unblock > OK.