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 ns1.carbon2u.com, not for smtp.carbon2u.com
Open
Cached
·
just now
86/100
SECURITY SCORE
Certificate Information
Subject
CN=ns1.carbon2u.com
Issuer
C=US, O=Let's Encrypt, CN=R13
Valid From
November 05, 2025
Valid Until
February 03, 2026
38 days
Public Key
RSA
4096 bit
Strong
Signature Algorithm
SHA256-RSA
SHA-256 Fingerprint
C5:ED:3B:30:22:68:4A:57:EA:7F:43:70:29:78:62:6C:3D:70:3E:5B:9E:11:DE:34:68:81:C3:55:07:AD:97:51
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
Present
max-age=63072000; includeSubdomains; preload
Content-Security-Policy
Missing
Not configured
X-Frame-Options
Excellent
DENY
X-Content-Type-Options
Good
nosniff
Referrer-Policy
Missing
Not configured
Permissions-Policy
Present
geolocation=(),midi=(),sync-xhr=(),microphone=(),camera=(),magnetometer=(),gyroscope=(),fullscreen=(self),payment=()
Recommendations
- • Increase HSTS max-age to at least 1 year and add includeSubDomains
- • Add Content-Security-Policy header to prevent XSS attacks
- • Add Referrer-Policy header (recommended: strict-origin-when-cross-origin)
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