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SECURITY SCORE
Certificate Information
Subject
CN=protonmail.com
Issuer
C=US, O=Let's Encrypt, CN=R13
Valid From
November 23, 2025
Valid Until
February 21, 2026
36 days
Public Key
RSA
4096 bit
Strong
Signature Algorithm
SHA256-RSA
SHA-256 Fingerprint
8E:B7:6B:27:CF:39:0F:48:40:E2:41:BB:98:19:51:06:14:4D:7F:28:DF:5C:92:CF:A1:AA:20:FF:94:DB:25:CE
Alternative Names
Security Configuration
TLS Protocols
TLS 1.2
TLS 1.3
Forward Secrecy
Supported
(Modern clients use PFS)
HTTP Security Headers
Status
Strict-Transport-Security
Excellent
max-age=31536000; includeSubDomains; preload
Content-Security-Policy
Basic
default-src; media-src; connect-src; +9 more
default-src 'self'; media-src https://static.zdassets.com https://res.cloudinary.com https://pmecdn.protonweb.com; connect-src 'self' wss: https://protonmail.zendesk.com https://ekr.zdassets.com blob: https://account.proton.me https://reports.proton.me https://telemetry.proton.me https://*.algolia.net https://*.algolianet.com https://go.getproton.me https://noembed.com https://boards-api.greenhouse.io https://proton.me https://*.paypal.com https://*.paypalobjects.com; script-src 'self' blob: 'unsafe-eval' 'unsafe-inline' https://static.zdassets.com https://pmecdn.protonweb.com https://www.youtube.com https://platform.twitter.com https://*.paypal.com https://*.paypalobjects.com; style-src 'self' 'unsafe-inline' https://pmecdn.protonweb.com https://*.paypal.com https://*.paypalobjects.com; font-src 'self' https://pmecdn.protonweb.com; img-src 'self' data: blob: https:; frame-src 'self' data: blob: https://www.youtube-nocookie.com https://platform.twitter.com https://*.paypal.com https://*.paypalobjects.com; object-src 'self' data: blob:; child-src 'self' data: blob: https://*.paypal.com https://*.paypalobjects.com; report-uri https://reports.proton.me/reports/csp; frame-ancestors 'self' https://*.proton.me;
X-Frame-Options
Missing
Not configured
X-Content-Type-Options
Good
nosniff
Referrer-Policy
Good
strict-origin-when-cross-origin
Permissions-Policy
Missing
Not configured
Recommendations
- • Improve CSP by adding more specific directives and removing 'unsafe-inline'
- • Add X-Frame-Options: DENY or SAMEORIGIN to prevent clickjacking
- • Consider adding Permissions-Policy to control browser features
CAA Records (Certificate Authority Authorization)
CAA Records
Configured
(Restricts certificate issuance)
Current Issuer
Authorized
(Matches CAA policy)
Authorized CAs
Incident Reporting
mailto:[email protected]
Recommendations
- • Consider using critical flag (flags=128) for stricter CAA enforcement
- • Consider adding 'issuewild' records to control wildcard certificate issuance