@SYNTAX:accept@
MODE <your nick> <+|->g

Works only in some IRC networks.

ACCEPT allows you to specify who you want to receive private messages
and notices from while you are in callerid (+g) mode.
When you have user mode +g enabled, messages from other users are blocked and
the sender is notified; you are also notified but at most once per minute.
IRC operators and services can usually send through +g.

The accept list is lost when you disconnect.
Users are automatically removed from the accept list if they quit, split
or change nick.

The argument is a comma-separated list of nicks to add or (when prefixed
with a '-') to remove. No output is returned for users successfully added
or removed.
If no arguments are given, your accept list is displayed (ACCEPT * on the
protocol level). 

Example:
    /ACCEPT user1,user2,-user3,-user4  - Adds user1 and user2 and removes
                                         user3 and user4.
 
See also: IGNORE, SILENCE