How can I prevent people from sending me Instant Messages?
Answer:
To prevent IM's from a single chatter,
right click on the chatter's name or Avatar, and select Ignore in the menu.
You will no longer see any IM's or room text from this chatter, and their
avatar will become a baghead. Additionally, their name will show only as a
red "ignored" in the room chatters list. The chatter will remain ignored
until you choose to take them off your ignore list.
To prevent IM's from all chatters, go to the Tools menu from within VPchat,
and select Preferences... Choose the "IMs" tab, and select the "Ignore all IMs" box.
You can customize the message people will receive when they attempt to
IM you.