ignore

ignore <player> [<minutes> | always]
  
  Ignores any say, tell, shout from <player> for the next <minutes>,
  or for forever. If no time is specified, 60 minutes is assumed.

  <player> can be set to 'channel', 'shout', 'pshout', 'wshout' 
  or 'all' as well.
  It is not possible to ignore archwizards.

ignore

  Shows who is ignored for how long time.

See also:
  unignore