HubSpot’s system also checks for publicly verifiable information about each account, such as an established web or social media presence. If any of this information looks questionable or can’t be easily verified, some tools in your account may be suspended for review.
Unfortunately, as the message states, some features will be permanently blocked and there aren’t any ways to bypass this on the free CRM.
For anyone that comes across this post in the future, it’s worth noting that you should establish your online presence first, to any extent possible (basic website, social profiles with focus on LinkedIn) before you start sending marketing emails - especially if you import a list of contacts and those contacts aren’t being created via inbound/adding themselves to your CRM.