Open
Cached
·
just now
92/100
SECURITY SCORE
Certificate Information
Subject
CN=*.fastmailusercontent.com
Issuer
C=US, O=Let's Encrypt, CN=R13
Valid From
December 28, 2025
Valid Until
March 28, 2026
67 days
Public Key
RSA
2048 bit
Adequate
Signature Algorithm
SHA256-RSA
SHA-256 Fingerprint
2D:37:0B:2B:65:6A:25:F3:B0:A0:C9:9D:D5:7D:9C:93:1A:01:4F:B0:4E:0E:74:68:33:7A:CC:7B:A1:ED:BB:C4
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
Good
default-src; style-src; img-src; +3 more
default-src 'none'; style-src 'unsafe-inline' 'self'; img-src data:; object-src 'self'; form-action 'none'; frame-ancestors https://*.fastmail.com;
X-Frame-Options
Missing
Not configured
X-Content-Type-Options
Good
nosniff
Referrer-Policy
Good
no-referrer
Permissions-Policy
Present
accelerometer=(), ambient-light-sensor=(), camera=(), document-domain=(), encrypted-media=(), gyroscope=(), magnetometer=(), microphone=(), midi=(), navigation-override=(), sync-xhr=(), usb=(), xr-spatial-tracking=()
Recommendations
- • Strengthen CSP by removing 'unsafe-eval'
- • Add X-Frame-Options: DENY or SAMEORIGIN to prevent clickjacking
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