CHANNEL MODE n

Usage: MODE <channel> +|-n
n - No external messages
Only people in the channel can speak to the channel. Without +n any user can send a message to the channel and it will be seen in the channel.
Privilege: channel operator
Examples:
/mode #movies +n

CHANNEL MODE N

Usage: MODE <channel> +|-N [<channel>]
N - Moderation receiver
This command is set to a channel that is receiving moderated messages from a +mM channel, it is a good way of scanning questions when you have a special event. To use both +M and +N modes you must be an network operator and you must be a channel op in both channels. The channel must be +m (moderated) for the messages to go to the receiving channel.
Privilege: network operator
Examples:
/mode #questions +N #event
See also: CMODE +m and CMODE +M