Open
Cached
·
just now
90/100
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
34 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; +8 more
default-src 'self'; media-src 'self' blob:; connect-src 'self' blob: https://proton.me https://*.proton.me; script-src 'self' 'wasm-unsafe-eval' blob: 'sha256-eAhF1Kdccp0BTXM6nMW7SYBdV0c3fZwzcC177TQ692g='; style-src 'self' 'unsafe-inline'; img-src http: https: data: blob: cid:; frame-src 'self' blob: https://mail-api.proton.me https://account.proton.me https://verify.proton.me https://calendar.proton.me https://drive.proton.me https://proton.me; object-src 'self' blob:; child-src 'self' data: blob:; report-uri https://reports.proton.me/reports/csp; frame-ancestors https://calendar.proton.me https://drive.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
Not Configured
(Any CA can issue certificates)
CAA Issues
- • No CAA records configured - any CA can issue certificates
Recommendations
- • Implement CAA records to restrict which CAs can issue certificates for your domain
- • This adds an extra layer of security against unauthorized certificate issuance
- • Example: Add CAA record 'example.com. CAA 0 issue "letsencrypt.org"'
- • Consider adding 'iodef' record to receive security incident reports