When answering things on the forum, original posters often get back to you with further information, further questions or other feedback. I've noticed that I often miss these updates because I forget to click the “subscribe to e-mail notifications” button on the right side of the post.
It would be amazing if there were some kind of toggle for “Automatically follow posts I replied to”.
Of course, it should still be possible to unfollow a specific post, but being able to set your own default like that would be very helpful, especially with the forum's popularity increasing with the number of Mendix developers.