ProtonMail’s world-class reliability is now backed by a 99.95% service level agreement (SLA)

Since we first opened to the public in 2014, ProtonMail has grown at an accelerating pace and is now the largest secure email provider in the world. With so many organizations depending on us for everyday communications, we are proud to offer an uptime guarantee for the services we provide. Our service level agreement (SLA) ensures that if downtime in any calendar month exceeds 0.05%, we will issue you a partial refund.

The new ProtonMail SLA is an expression of our confidence in our systems. We have exceeded 99.95% uptime for the past two years, and we continue to work hard and invest heavily in site reliability.

Site reliability engineering at ProtonMail

ProtonMail owns and controls its network, located inside three geographically diverse datacenters in Switzerland. Because of the high security needs of our users, we selected each datacenter according to high security and reliability standards (each datacenter is ISO 27001 certified). We implement several layers of redundancy, both within each datacenter and across our network. At the server level, our infrastructure is designed to automatically reroute traffic if any servers go offline. Redundancy in our servers allows us to add servers and take servers offline without downtime.

ProtonMail is a member of the Réseaux IP Européens Network Coordination Centre (RIPE NCC), providing us with our own dedicated allocation of IPv4 and IPv6 addresses, which allows us to control IP reputation and isolate our network infrastructure from other potential points of failure. You can read more details about our network and infrastructure here.

Strong defenses against cyber attack

Our infrastructure also provides strong protections against cyber attacks that might seek to reduce our uptime. ProtonMail provides state-of-the-art protection against DDoS (distributed denial of service) attacks. Hosting your emails with ProtonMail means that if your business or website ever comes under DDoS attack (or if another business hosted at the same location comes under attack), your email will stay online and accessible, and you won’t lose your most important way of communicating with customers. This is important because DDoS is becoming one of the most popular ways to attack and disrupt businesses.

ProtonMail also utilizes end-to-end encryption and zero-access encryption to ensure that even in the unlikely event of a data breach, the contents of your emails will stay secure.

Redundancy to prevent downtime and data loss

A high level of data redundancy means that ProtonMail is very resistant to data loss. ProtonMail’s three datacenters are geographically distributed across different regions of Switzerland. All data is replicated across multiple sites so we can suffer multiple catastrophic failures before experiencing actual data loss. Furthermore, our infrastructure is designed even to survive the loss of an entire datacenter due to natural or man-made disasters.

We also have a rigorous system of backups. Each data storage system has multiple backups, which can be enabled if there is ever a failure of the primary database. There are also secondary backups in case the first backup fails. Data loss is further prevented by automated and regular backups of all customer data.

Transparent and rapid customer communications

We strongly believe in providing transparent and timely information about any service outages. You can find real-time status information about ProtonMail and ProtonVPN at, and we post updates and respond to questions on Twitter, Facebook, and Reddit.

Our success is predicated on strong security and consistent uptime, and site reliability is one of our highest priorities. Our newly introduced SLA is a reflection of this focus and allows your organization to use ProtonMail with confidence. For more information, you can read the full details of our SLA in our Terms and Conditions.

Best Regards,
The ProtonMail Team

Learn more about how ProtonMail can help secure your business communications.

ProtonMail provides free encrypted email accounts to the public.

We also provide a free VPN service to protect your privacy.

About the Author

Irina M

Irina is one of Proton's longest-serving team members, charged with strengthening and growing our brand and the Proton community. With a background in visual design, events management, and digital marketing, she strongly supports the protection of private data and contributes to building a better internet for generations to come.