“Accounts such as these have a high risk of being attacked by criminals or state-backed hackers,” writes Proton’s Dingchao Lu. “We are now ready to provide the same level of advanced protection and support that we reserved for these VIPs to any Proton user that wants it through the Proton Sentinel program.”

You don’t have to fall into one of those categories to use Proton Sentinel, but you do have to be a paying Proton user: a Visionary, Lifetime, Family, Unlimited, or Business plan is required, and you can see details of all the plans here.

A lot of the work that Proton Sentinel does goes on behind the scenes, and you’ll find that Proton itself doesn’t go into too much detail about how it functions—which is sensible if you want to minimize the chances of someone else getting around it.

The advanced security protection it offers includes strict challenges for “suspicious” login attempts, typically those from devices that you don’t normally use and parts of the world that you’re not normally in. You might find yourself asked to confirm more of your logins to Proton services with Sentinel enabled, but it’s worth it for the extra peace of mind.

Proton says that suspicious logins are flagged by automated systems and then escalated to human security analysts, around the clock. Any support requests you file related to account security will also get escalated to trained security specialists, meaning that if there is a security problem, it’s going to be dealt with more quickly.

Related to this stricter policy on logins, Proton Sentinel also gives you access to detailed security logs inside your account, listing attempts to log in using your credentials, as well as other key actions you need to be aware of (such as password changes.)