This isn't quite that degree of fine-grained control. You can turn email notifications on or off here: https://discussions.apple.com/user-preferences!input.jspa
If they are on you get a notification for all content that you are "following". You will automatically follow any thread that you contribute to, and any where you have clicked the blue follow link at the top of the thread. You will also receive notifications for all activity in any forum that you've chosen to follow. You can turn off all of these individually, and then unfollow any thread that you've made a comment in but don't want to hear from again.
Alternatively you might like to turn off all email notifications and use these links to follow responses to your posts, the first three will highlight threads with new activity:
Authored Discussions
Participated Discussions
Following Discussions
Recently Viewed Discussions
See also Site map of Communities and Categories.
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