Effective immediately for members: You will no longer receive email notifications when a topic you follow gets updated.
You will still receive email notifications for private messages and other website services.
You can still subscribe to topics as you always have and those topics will appear on your account overview when you click your profile picture in the corner. The only difference is you won't get an email notification when they get a new comment. You'll have to check your topic list on your own.
The subscription feature was more popular than I realized and was sending out a ton of emails everyday so that raised a flag with the vendor. That's what you get when you go with the "free" plan :)
I'll need to adjust some things to make the email sending smarter for those notifications but until then, they have been disabled. Sorry for any inconvenience. I have no real timeline for a fix but hopefully sooner than later.