Identity
29
C
dexcom.com
Posture Score: 70/100
Scanned May 17, 2026 at 8:36 PM UTC
Attack Surface
83
Reputation
99
Identity Findings
Critically weak DKIM key (~1000 bits) for selector 'cm'
RSA keys shorter than 1024 bits are trivially breakable. RFC 8301 requires minimum 1024 bits.
💡 Immediately generate a 2048-bit RSA key pair.
Weak DKIM RSA key (~1296 bits) for selector 'selector1'
RSA keys shorter than 2048 bits are considered weak. Current key is approximately 1296 bits.
💡 Generate a new 2048-bit (or larger) RSA key pair and update the DKIM record.
Weak DKIM RSA key (~1296 bits) for selector 's2'
RSA keys shorter than 2048 bits are considered weak. Current key is approximately 1296 bits.
💡 Generate a new 2048-bit (or larger) RSA key pair and update the DKIM record.
Weak DKIM RSA key (~1296 bits) for selector 'mandrill'
RSA keys shorter than 2048 bits are considered weak. Current key is approximately 1296 bits.
💡 Generate a new 2048-bit (or larger) RSA key pair and update the DKIM record.
Weak DKIM RSA key (~1000 bits) for selector 'cm'
RSA keys shorter than 2048 bits are considered weak. Current key is approximately 1000 bits.
💡 Generate a new 2048-bit (or larger) RSA key pair and update the DKIM record.
DKIM in testing mode for selector 'cm'
The t=y flag indicates DKIM is in testing mode. Receivers may not enforce DKIM failures.
💡 Remove the t=y flag once DKIM signing is verified in production.
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.dexcom.com/.well-known/mta-sts.txt
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.
SOA expire value too short
The SOA expire value is 259200s (<604,800s / 7 days). Secondary nameservers may stop serving the zone prematurely.
💡 Increase the SOA expire value to at least 604800 seconds (7 days).
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"
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@dexcom.com").
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.
Very low TTL on TXT records: 94s
35 TXT records have a TTL of 94s or less (below 300s).
💡 Increase the TTL to at least 300 seconds unless frequent changes are expected.
Very low TTL on SPF record: 94s
The SPF record has a TTL of 94s or less (below 300s).
💡 Increase the TTL to at least 300 seconds unless frequent changes are expected.
SPF record is valid
The SPF record is properly configured with valid syntax and within lookup limits.
SPF record length OK (233 bytes)
SPF record is within safe DNS packet size limits.
DKIM key strength indicates modern key management
All DKIM keys use RSA-2048+ or Ed25519, consistent with current best practices.
All external report destinations authorized
External DMARC report destinations have valid authorization records per RFC 7489 §7.1.
Subdomains protected (sp=reject)
DMARC subdomain policy enforces quarantine or reject on unauthenticated subdomain mail.
MX records are valid
All MX records are properly configured.
ARC support likely available
MX server software appears to support ARC headers for authentication preservation.
Meets bulk sender authentication requirements
Domain has SPF, DKIM, and DMARC — meeting Google/Yahoo 2024 bulk sender requirements for email authentication.
SMTP security checks passed
No open relay, VRFY/EXPN, or banner disclosure issues detected.
SMTP RFC 5321 compliance checks passed
The mail server accepts postmaster@ and abuse@ and uses a valid FQDN in EHLO.
NS delegation is properly configured
All nameservers are responsive, consistent, and properly secured.
DNS responses are consistent across all nameservers
All authoritative nameservers return consistent answers with proper AA flags.
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.
DMARC alignment: adkim=r, aspf=r
DKIM alignment is relaxed, SPF alignment is relaxed.
DMARC failure reporting: fo=1
Failure reports generated when any authentication mechanism fails.
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.
Deprecated DMARCbis tags found: pct, ri
The DMARC record contains tags deprecated in DMARCbis: pct, ri. Consider removing these for forward compatibility.
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.
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.
No DANE/TLSA records found
DANE is not configured for any MX server. This is optional but provides strong certificate binding.
No BIMI record found
BIMI is not configured. Your brand logo will not display in supporting email clients.
Open mail ports on dexcom-com.mail.protection.outlook.com
Detected open mail-related ports: 25
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.
MX IP network diversity
All MX IPs are in the same /16 network. Consider diversifying across networks for resilience.
SOA record parameters
Serial: 38, Refresh: 21600s, Retry: 3600s, Expire: 259200s, Min TTL: 300s
Attack Surface Findings
Weak DNSSEC RSA key: 336 bits
The DNSKEY uses an RSA key of 336 bits, below the recommended 2048 bits.
💡 Generate a new DNSKEY with at least 2048-bit RSA or migrate to ECDSA/Ed25519.
Weak DNSSEC RSA key: 336 bits
The DNSKEY uses an RSA key of 336 bits, below the recommended 2048 bits.
💡 Generate a new DNSKEY with at least 2048-bit RSA or migrate to ECDSA/Ed25519.
Domain enumerability: low
The domain has low enumerability. Proper NSEC3 configuration and limited CT exposure reduce the attack surface.
All MX records resolve correctly
No dangling MX records detected — all MX hostnames resolve to valid IP addresses.
Explicit MX records present
The domain has explicit MX records — no implicit A-record fallback delivery.
No internal information leakage detected
No non-routable IP addresses or internal references were found in public DNS records.
No excessive DNS information exposure detected
No HINFO, LOC, RP records, version disclosures, or zone walking vulnerabilities were found.
No email autodiscovery endpoints detected
No Microsoft Autodiscover, Mozilla Autoconfig, or email SRV records were found.
15 subdomain(s) discovered for dexcom.com
Subdomains were enumerated via Certificate Transparency logs, DNS wordlist brute-forcing, and DNS record analysis.
0 certificate(s) found in CT logs
Certificate Transparency logs contain 0 certificate(s) for dexcom.com and its subdomains. Each certificate reveals subdomain names.
NSEC3 authenticated denial of existence
The domain uses NSEC3 with 1 iteration(s) and salt 'F7A7DCA9C27F33F1'.
DNSSEC is enabled
DNSKEY and/or DS records are present, indicating DNSSEC is configured.
Reputation Findings
HSTS enabled but missing preload directive on dexcom.com
Strict-Transport-Security: max-age=31536000
💡 Add the "preload" directive to the HSTS header and submit the domain to hstspreload.org.
Not listed on any DNS blacklists
Domain and MX IPs checked against 55 DNSBLs — no listings found.
security.txt present
Found security.txt at https://dexcom.com/.well-known/security.txt.
TLS certificate valid for 88 days
Certificate for dexcom.com expires on 2026-08-14.
Certificate issued by WE1
The certificate for dexcom.com is issued by a third-party CA.
Signature algorithm: ecdsa-with-sha256
The certificate for dexcom.com uses an acceptable signature algorithm.
ECC key: 256 bits
The certificate for dexcom.com uses an adequate ECC key of 256 bits.
SCTs present in certificate
The certificate for dexcom.com contains Signed Certificate Timestamps.
No weak ciphers detected
No known weak cipher suites detected on dexcom.com.
No disposable email provider MX records
MX records for dexcom.com do not match known disposable email provider patterns.
No wildcard MX records
No wildcard MX records detected for dexcom.com.
TLD has good reputation
The .com TLD is not on known abuse watchlists.
DMARC reporting destinations look legitimate
DMARC rua/ruf addresses do not point to known URL shortener services.
MX records point to stable infrastructure
No MX records point to known dynamic DNS service domains.
Strong TLS configuration on primary MX
Primary MX (dexcom-com.mail.protection.outlook.com) uses TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 including Forward Secrecy.
SMTP banner from hosted mail provider
The MX (dexcom-com.mail.protection.outlook.com) is a hosted mail service. Banner alignment is managed by the provider and not actionable by the domain owner.
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.
Abuse contacts found for MX IPs
Abuse contact information retrieved via abusix.org DNS lookup.
PhishTank — API key required
PhishTank phishing database check requires an API key.
Sender Score — API key required
Sender Score reputation check requires an API key.
Cisco Talos — API key required
Cisco Talos IP reputation check requires an API key.
Could not connect to webmail.dexcom.com
HTTPS request to https://webmail.dexcom.com failed or timed out.
WHOIS lookup failed
Could not retrieve WHOIS data for dexcom.com.
Could not determine domain age
WHOIS creation date could not be parsed for dexcom.com.
Bulletproof Hosting Detection — API key required
Checking IPs against known bulletproof hosting providers requires a threat intelligence API key.
Threat Intelligence Feeds — API key required
Checking domain against threat intelligence feeds requires API keys (e.g., VirusTotal, AbuseIPDB).
Typosquat detected: dxcom.com (has MX!), dexcm.com (has MX!), dexco.com (has MX!), rexcom.com (has MX!), xexcom.com (has MX!)
19 registered lookalike domain(s) that could be used for phishing against your brand. Showing top 5 of 19. Domains with MX records can send and receive email, making them high-risk phishing vectors.
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: reject
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: reject
⚠️ 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: dexcom-com.mail.protection.outlook.com
PTR record proves mail server legitimacy
MX: dexcom-com.mail.protection.outlook.com
Mail server at 52.101.41.26
→
PTR Record
Reverse DNS: mail-sj0pr03cu01702.inbound.protection.outlook.com
Mail Server Reputation: dexcom-com.mail.protection.outlook.com
RBL check ensures server is not blacklisted
MX: dexcom-com.mail.protection.outlook.com
Mail server at 52.101.41.26
→
RBL Status
Not blacklisted
Enforced Encryption Chain
MTA-STS enforces TLS encryption to prevent man-in-the-middle attacks
TLS Support
Mail servers support TLS encryption
→
MTA-STS Policy
MTA-STS not configured
⚠️ MTA-STS policy is missing. Even with TLS support, you lack the enforcement layer that prevents attackers from stripping encryption (downgrade attacks).
Brand Identity Chain
BIMI displays your logo in email clients, but requires DMARC enforcement
DMARC Enforcement
DMARC policy: reject
→
BIMI Record
BIMI not configured
⚠️ BIMI record is missing. Even with DMARC enforcement, you need to configure BIMI to display your brand logo in supported email clients.
TLS Monitoring Chain
TLS-RPT provides reports about TLS connection failures
TLS Support
Mail servers support TLS encryption
→
TLS-RPT Reporting
TLS-RPT not configured
⚠️ TLS-RPT is not configured. Without TLS reporting, you have no visibility into TLS connection failures that may be impacting email delivery.
Security Checks
MX Records
✓
SPF Record
✓
DKIM Record
✗
DMARC Policy
✓
BIMI Record
✗
CAA Records
✗
DNSSEC
✓
MTA-STS
✗
TLS-RPT
✗
Embed Badge
Display your domain's security grade on your website or README:
<img src="https://scan.ractermx.com/badge/dexcom.com.svg" alt="Email Security Grade">
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