We've had a lot of reports from users with Gmail addresses that our invitation emails aren't being delivered to them. If you're interested in getting moved to Plesk or creating a new account you have two options:
1) Contact Gmail support and ask them to deliver emails from heliohost.org domains to your inbox.
2) Use literally any other email address other than Gmail.
We've contacted Gmail support ourselves regarding this issue and they helped us fix a few issues that might be causing