The system generates notifications for you when other users directly reply to your posts. Use these options to override and expand the default behaviour:

• New threads
  Check this option if you wish to be notified when new threads are posted to this forum.
• All activity
  Check this option if you wish to be notified about most events inside this forum. For example, the posting of new threads, and also the posting of new replies.
• Ignore All
  Check this option if you do not wish to be notified about any events in this forum. This means a notification will not be generated even if somebody replies directly to a posting you have made

Email notifications are aggregated and sent to you periodically according to your account settings. However if somebody replies directly to a posting you have made, an email notification is sent as soon as possible.