You can move to Morty instead to avoid the inactivity requirement if you want. That server replaces the activity requirement with a $1/month fee instead.
Otherwise, as above, this requirement has been the same for 15+ years. Not sure where you read the incorrect information you have, but the instructions in Unknown025's post are correct. The only thing that avoids suspension for inactivity aside from paying for Morty is to log in at https://heliohost.org/login/ once every 30 days. Email use, FTP, web traffic etc. does not count as activity.
Also, for the support and reminder emails not working, it's because you unsubscribed. If you unsubscribe from any of our emails, you will receive NO emails from us, with the sole exception of Terms of Service update notices (which are required for legal reasons). That means you can't use email support and won't receive inactivity reminders.
Do you want me to resubscribe you so you can use support and you're alerted prior to inactivity suspension next time?