
MODE %|<your nick>|<channel> [<mode> [<mode parameters>]]

Irssi knows these channel modes:

     i - Invite only - People can't join to channel without being
          /INVITEd, or being in invite list (+I, see below).
     m - Moderated - People who don't have voices (+v) can't send
          messages to channel
     p - Private - People who aren't joined to channel can't see it
          for example with /WHOISing people who are in channel.
     s - Secret - Like private, but the channel isn't displayed in
          /LIST's output.
     n - No external msgs - Without this mode, anyone can send messages
          to channel without even being joined.
     t - Topic can be changed only by channel operators.

     k <key> - Channel password (aka. key) - The channel can't be joined
                without specifying the channel key (see section 6.2).

     l <count> - User limit - No more than <count> people can join to
         	 channel. This can be overridden with /INVITE with some
         	 servers.

         	 This is usually used for protecting channel from join
         	 flooding, like some bot allows max. 5 users to join in
         	 one minute or so.

     a - Anonymous - No-one's nick name, host or anything else can be
          seen. All messages, joins, parts, modes, etc. are seen as coming
          from nick "anonymous", this could be pretty confusing but nice
          feature if you want total anonymity. This mode can only be set,
          never unset. This mode isn't supported by all servers.

          NOTE: there is/was one bug :) Channel operators can guess if some
          nick might be in the channel and try to kick it. If nick was in
          channel, everyone will see the nick that was kicked.

     r - Re-op - If a channel becomes opless for longer than LDCTL (5400,
         by default) seconds, op a random person on the channel (or everyone
          if channel has less than 6 members). This works only on !channels.
          This mode can only be set and unset by channel creator.

     b - Set/remove ban. For example MODE #channel +b *!*@*.org bans
          everyone from .org domain.

          If someone from .org domain was already in channel before the
          ban was set, he/she couldn't be able to write any messages to
          channel (doesn't work with all servers).

          Ban can also be overridden with /INVITE, although many stupid
          IRC clients automatically kick the user out because they see
          the ban and think that because of it the user shouldn't be in
          the channel (doesn't work with all servers).

     e - Ban exceptions. You could for example ban everyone from
          *!*@*.org but set ban exception to *!*@*.host.org - works only
          in IRCnet/EFnet servers.

     I - Invite list. If channel is invite only (+i), people in this
          list can join it without being /INVITEd - works only in
          IRCnet servers.

          This is excellent for in-country channels that don't want
          foreigners (spammers!) to join the channel, for example setting
          channel's mode to +i and +I *!*@*.fi allows only finnish people
          to join the channel. In addition to this, there's usually a bot
          in the channels and sending /MSG bot invite command to it
          /INVITEs you to the channel.

          The ':' feature in channel modes is quite similiar, see section
          6.2.

     O - Channel owner, the nick who creates a !channel receives this
          mode. It isn't displayed anywhere, you can't pass it to anyone
          else and you can't regain it again. This is needed for setting
          +r mode in channel when it's first created.

     o <nick> - Grant or revoke channel operator status from nick
     v <nick> - Grant or revoke voice status from nick, only people with
         	+v (or +o) can talk to channel when it's moderated (+m).

You can send multiple mode changes with one mode command:

/MODE #channel +nto-o+v nick1 nick2 nick3

This would set channel's mode to +nt, give ops to nick1, take ops from nick2 and give voices to nick3.

You can set only limited number of modes that requires argument in one command. In IRCnet it's 3, in EFnet it's 4 and in many others it's 6. If it's not known, Irssi defaults to 3. Irssi will also automatically split them, so you can use /MODE +oooooo n1,n2,.. command to op 6 people and Irssi will split it to two commands in IRCnet/EFnet.

See also: OP, DEOP, VOICE, DEVOICE, BAN, UNBAN

