← Back to Scanner

cerby.com

Name: cerby.com Email Security Posture Assessment
Creator: RacterMX

Posture Score: 87/100

Scanned May 9, 2026 at 4:35 AM UTC

Score History

Identity

Attack Surface

Reputation

Identity Findings

No MTA-STS record found

Without MTA-STS, mail transport encryption cannot be enforced and is vulnerable to downgrade attacks.

💡 Publish a _mta-sts TXT record and host a policy file at https://mta-sts.cerby.com/.well-known/mta-sts.txt

medium

STARTTLS without MTA-STS or DANE protection

STARTTLS alone is vulnerable to downgrade attacks. Neither MTA-STS nor DANE is configured to enforce encryption.

💡 Deploy MTA-STS and/or DANE to protect against STARTTLS stripping attacks.

medium

No CAA records found

No CAA records are configured. Any certificate authority can issue certificates for this domain.

💡 Add CAA records to restrict certificate issuance. Example: 0 issue "letsencrypt.org"

medium

DMARC percentage is 75% (not fully enforced)

Only 75% of messages are subject to the DMARC policy. The remaining messages are treated as p=none.

💡 Increase pct to 100 once confident in SPF/DKIM alignment.

low

No TLS-RPT record found

Without TLS-RPT, you will not receive reports about TLS negotiation failures.

💡 Publish a _smtp._tls TXT record (e.g. "v=TLSRPTv1; rua=mailto:tls-reports@cerby.com").

low

SPF has ip4 mechanisms but no ip6

The SPF record authorizes IPv4 addresses but not IPv6. Your MX servers have AAAA records, so IPv6 mail delivery is possible without SPF authorization.

💡 Add ip6: mechanisms to the SPF record for your IPv6 mail server addresses.

low

Slow DNS response from ns-32.awsdns-04.com: 2085.8ms

The nameserver ns-32.awsdns-04.com responded in 2085.8ms, exceeding the 500ms threshold.

💡 Investigate network latency or performance issues on ns-32.awsdns-04.com.

low

Very low TTL on MX records: 26s

5 MX records have a TTL of 26s or less (below 300s).

💡 Increase the TTL to at least 300 seconds unless frequent changes are expected.

low

Very low TTL on NS records: 26s

4 NS records have a TTL of 26s or less (below 300s).

💡 Increase the TTL to at least 300 seconds unless frequent changes are expected.

low

Very low TTL on DMARC record: 266s

The DMARC record has a TTL of 266s or less (below 300s).

💡 Increase the TTL to at least 300 seconds unless frequent changes are expected.

low

NS TTL mismatch between parent and authoritative zone

The NS record TTL in the parent zone (~26s) differs significantly from the authoritative zone (~60s).

💡 Align NS record TTLs between the parent zone delegation and the authoritative zone.

low

SPF record is valid

The SPF record is properly configured with valid syntax and within lookup limits.

pass

SPF record length OK (154 bytes)

SPF record is within safe DNS packet size limits.

pass

DKIM records are valid

DKIM records found and validated for selectors: google

pass

DKIM cryptographic configuration is compliant

No RFC 8301 compliance issues detected in DKIM key configuration.

pass

DKIM key strength indicates modern key management

All DKIM keys use RSA-2048+ or Ed25519, consistent with current best practices.

pass

No external DMARC report destinations

All DMARC report URIs point to the same domain — no external authorization needed.

pass

Subdomains protected (sp=quarantine)

DMARC subdomain policy enforces quarantine or reject on unauthenticated subdomain mail.

pass

5 MX records with 5 unique IPs

Multiple MX records provide mail delivery redundancy.

pass

BIMI record is valid

BIMI is properly configured with a valid logo and DMARC enforcement.

pass

VMC URL is accessible

The BIMI VMC authority URL is reachable and returns a valid response.

pass

ARC support likely available

MX server software appears to support ARC headers for authentication preservation.

pass

Meets bulk sender authentication requirements

Domain has SPF, DKIM, and DMARC — meeting Google/Yahoo 2024 bulk sender requirements for email authentication.

pass

SMTP security checks passed

No open relay, VRFY/EXPN, or banner disclosure issues detected.

pass

SMTP RFC 5321 compliance checks passed

The mail server accepts postmaster@ and abuse@ and uses a valid FQDN in EHLO.

pass

NS delegation is properly configured

All nameservers are responsive, consistent, and properly secured.

pass

DKIM2 not detected

No DKIM key record with v=2 was found across common selectors. DKIM2 is an emerging standard and not yet widely deployed.

informational

DMARC alignment: adkim=r, aspf=r

DKIM alignment is relaxed, SPF alignment is relaxed.

informational

DMARCbis np tag absent

The DMARC record does not include the np (non-existent subdomain policy) tag. Consider adding np=reject to protect non-existent subdomains under DMARCbis.

informational

Deprecated DMARCbis tags found: pct

The DMARC record contains tags deprecated in DMARCbis: pct. Consider removing these for forward compatibility.

informational

DMARCbis psd tag absent

The DMARC record does not include the psd (public suffix domain) indicator. Consider adding psd=n to explicitly identify this as an organizational domain.

informational

Shared/free email hosting detected: aspmx.l.google.com

The MX record points to a known shared or free email hosting provider.

informational

Shared/free email hosting detected: alt3.aspmx.l.google.com

The MX record points to a known shared or free email hosting provider.

informational

Shared/free email hosting detected: alt4.aspmx.l.google.com

The MX record points to a known shared or free email hosting provider.

informational

Shared/free email hosting detected: alt1.aspmx.l.google.com

The MX record points to a known shared or free email hosting provider.

informational

Shared/free email hosting detected: alt2.aspmx.l.google.com

The MX record points to a known shared or free email hosting provider.

informational

REQUIRETLS not advertised

The primary MX does not advertise REQUIRETLS (RFC 8689). This is an emerging standard — MTA-STS and DANE provide adequate TLS enforcement for most deployments.

informational

No DANE/TLSA records found

DANE is not configured for any MX server. This is optional but provides strong certificate binding.

informational

Open mail ports on aspmx.l.google.com

Detected open mail-related ports: 25

informational

RFC 8058 one-click unsubscribe assessment

DKIM signing is configured. RFC 8058 compliance depends on List-Unsubscribe and List-Unsubscribe-Post headers being included in outbound messages and DKIM signatures.

informational

MX IP network diversity

MX IPs span 5 different /16 networks, providing good diversity.

informational

SOA record parameters

Serial: 1, Refresh: 7200s, Retry: 900s, Expire: 1209600s, Min TTL: 86400s

informational

Attack Surface Findings

DNS ANY query returns 40 record(s)

The DNS server responds to ANY queries with 40 record(s), creating significant DNS amplification risk.

💡 Configure the DNS server to refuse or minimize ANY query responses per RFC 8482.

medium

DNSSEC is not enabled

No DNSKEY or DS records were found. DNS responses are not cryptographically authenticated.

💡 Enable DNSSEC by generating DNSKEY records and publishing DS records at the registrar.

medium

Domain enumerability: low

The domain has low enumerability. Proper NSEC3 configuration and limited CT exposure reduce the attack surface.

low

All MX records resolve correctly

No dangling MX records detected — all MX hostnames resolve to valid IP addresses.

pass

Explicit MX records present

The domain has explicit MX records — no implicit A-record fallback delivery.

pass

No internal information leakage detected

No non-routable IP addresses or internal references were found in public DNS records.

pass

5 subdomain(s) discovered for cerby.com

Subdomains were enumerated via Certificate Transparency logs, DNS wordlist brute-forcing, and DNS record analysis.

informational

0 certificate(s) found in CT logs

Certificate Transparency logs contain 0 certificate(s) for cerby.com and its subdomains. Each certificate reveals subdomain names.

informational

Wildcard DNS record detected

A wildcard DNS record exists for *.cerby.com, resolving to 54.230.114.102, 54.230.114.114, 54.230.114.9, 54.230.114.60. Wildcard records make subdomain brute-forcing less effective but may mask misconfigurations.

informational

Microsoft Autodiscover endpoint detected

The Autodiscover endpoint at autodiscover.cerby.com responded with HTTP 404.

informational

Reputation Findings

SMTP banner mismatch: mx.google.com

The SMTP banner identifies as 'mx.google.com' but the MX hostname is 'aspmx.l.google.com' and PTR resolves to 'dj-in-f27.1e100.net'. Microsoft and other receivers flag this mismatch as suspicious infrastructure.

💡 Configure the SMTP server banner to match the MX hostname or PTR record (aspmx.l.google.com).

high

HSTS enabled but missing preload directive on cerby.com

Strict-Transport-Security: max-age=31536000

💡 Add the "preload" directive to the HSTS header and submit the domain to hstspreload.org.

low

HSTS enabled with preload on webmail.cerby.com

Strict-Transport-Security: max-age=31536000; includeSubdomains; preload

pass

security.txt present

Found security.txt at https://cerby.com/.well-known/security.txt.

pass

TLS certificate valid for 239 days

Certificate for cerby.com expires on 2027-01-03.

pass

Certificate issued by Amazon RSA 2048 M01

The certificate for cerby.com is issued by a third-party CA.

pass

Signature algorithm: rsa-sha256

The certificate for cerby.com uses an acceptable signature algorithm.

pass

RSA key: 2048 bits

The certificate for cerby.com uses an adequate RSA key of 2048 bits.

pass

SCTs present in certificate

The certificate for cerby.com contains Signed Certificate Timestamps.

pass

No weak ciphers detected

No known weak cipher suites detected on cerby.com.

pass

Domain valid for 363 days

Domain cerby.com expires on 2027-05-07.

pass

Domain transfer and delete locks enabled

Domain cerby.com has clientTransferProhibited and clientDeleteProhibited locks.

pass

TLD has good reputation

The .com TLD is not on known abuse watchlists.

pass

DMARC reporting destinations look legitimate

DMARC rua/ruf addresses do not point to known URL shortener services.

pass

MX records point to stable infrastructure

No MX records point to known dynamic DNS service domains.

pass

Strong TLS configuration on primary MX

Primary MX (aspmx.l.google.com) uses TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 including Forward Secrecy.

pass

Google Safe Browsing DNS check — no flag detected

DNS-based Safe Browsing lookup returned no results. Full verification requires the Google Safe Browsing API key.

informational

Abuse contact lookup failed

Could not query abuse contact information.

informational

PhishTank — API key required

PhishTank phishing database check requires an API key.

informational

Sender Score — API key required

Sender Score reputation check requires an API key.

informational

Cisco Talos — API key required

Cisco Talos IP reputation check requires an API key.

informational

WHOIS registration data

Registrar: GoDaddy.com, LLC | Created: 2005-05-07 | Expires: 2027-05-07 | Updated: 2026-05-08

informational

WHOIS privacy protection enabled

Domain cerby.com has WHOIS privacy/redaction enabled.

informational

Typosquat detected: crby.com (has MX!), cery.com (has MX!), cerb.com (has MX!), creby.com (has MX!), crrby.com (has MX!)

21 registered lookalike domain(s) that could be used for phishing against your brand. Showing top 5 of 21. Domains with MX records can send and receive email, making them high-risk phishing vectors.

informational

Dependency Chains

DMARC Authentication Chain (SPF)

DMARC uses SPF to verify that emails come from authorized servers

SPF Record SPF record found and configured → DMARC Policy DMARC policy: quarantine

DMARC Authentication Chain (DKIM)

DMARC uses DKIM to verify that emails have not been tampered with

DKIM Signature DKIM signature missing → DMARC Policy DMARC policy: quarantine

⚠️ DKIM signature is missing. DMARC relies on DKIM to verify email integrity and prevent tampering. Without DKIM, DMARC alignment will fail for cryptographic verification.

Mail Server Identity: aspmx.l.google.com

PTR record proves mail server legitimacy

MX: aspmx.l.google.com Mail server at 209.85.203.27 → PTR Record Reverse DNS: dh-in-f27.1e100.net

Mail Server Identity: alt3.aspmx.l.google.com

PTR record proves mail server legitimacy

MX: alt3.aspmx.l.google.com Mail server at 192.178.213.27 → PTR Record Reverse DNS: yugrqzs-in-f27.1e100.net

Mail Server Identity: alt4.aspmx.l.google.com

PTR record proves mail server legitimacy

MX: alt4.aspmx.l.google.com Mail server at 142.251.127.26 → PTR Record Reverse DNS: lcfrai-in-f26.1e100.net

Mail Server Identity: alt1.aspmx.l.google.com

PTR record proves mail server legitimacy

MX: alt1.aspmx.l.google.com Mail server at 173.194.76.27 → PTR Record Reverse DNS: ws-in-f27.1e100.net

Mail Server Identity: alt2.aspmx.l.google.com

PTR record proves mail server legitimacy

MX: alt2.aspmx.l.google.com Mail server at 142.250.102.26 → PTR Record Reverse DNS: rb-in-f26.1e100.net

Mail Server Reputation: aspmx.l.google.com