DNS Gurus

SSL Verification Bypassed

The server's SSL certificate could not be verified. The analysis was completed using insecure mode. Data may be less reliable.

Reason:

Hostname Mismatch - certificate is issued for autoconfig.startmail.com, blog.startmail.com, classic.startmail.com, forum.startmail.com, mail.startmail.com, mta-sts.startmail.com, mta-sts.use.startmail.com, startmail.com, strt.ml, not for web2.startmail.com

Cached · just now
76/100 SECURITY SCORE

Certificate Information

Subject
CN=startmail.com
Issuer
C=US, O=Let's Encrypt, CN=R13
Valid From
December 16, 2025
Valid Until
March 16, 2026 74 days
Public Key
RSA 4096 bit Strong
Signature Algorithm
SHA256-RSA
SHA-256 Fingerprint
02:B3:AE:E7:FD:B5:89:91:F3:AB:5F:70:1B:AF:35:6B:E4:01:9E:EA:BF:6F:9F:99:3A:A6:66:B7:97:AB:74:4F
Alternative Names
12 domains

Security Configuration

TLS Protocols
TLS 1.2 TLS 1.3
Forward Secrecy
Supported (Modern clients use PFS)

HTTP Security Headers

Status
Strict-Transport-Security
Missing
Not configured
Content-Security-Policy
Missing
Not configured
X-Frame-Options
Missing
Not configured
X-Content-Type-Options
Missing
Not configured
Referrer-Policy
Missing
Not configured
Permissions-Policy
Missing
Not configured
Recommendations
  • • Add Strict-Transport-Security header with max-age of at least 1 year
  • • Add Content-Security-Policy header to prevent XSS attacks
  • • Add X-Frame-Options: DENY or SAMEORIGIN to prevent clickjacking
  • • Add X-Content-Type-Options: nosniff
  • • Add Referrer-Policy header (recommended: strict-origin-when-cross-origin)
  • • 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