"Manage Email Notifications: Subscribe or Unsubscribe"
The link allows you to edit your preferences for notifications related to messages posted inside this forum.
If you enter some other forum ("Ask Trapper"), and you locate a similar link under any message posted inside that forum, it will allow you to edit your preferences for notifications related to that particular forum.
You can subscribe for or unsubscribe from receiving notifications on several levels.
On the level of the whole forum, after any new message is posted. (That is what is happening to you right now.)
On the level of the whole forum, after just a new topic message is posted.
On the level of a single thread, after any message is posted inside a single thread.
On the level of a single message, after a new reply is posted to that particular message.
You can also stop all notifications with a single click.
If you edit your account, it allows you to stop all notifications, regardless of what you selected before.