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Security report for mailgun.com

Transactional Email API Service For Developers | Mailgun · Technology · N/a

Low risk. 2 critical or high findings in SSL/TLS.

Security score

82/100

Risk levelLow

0–100, higher is better. How it is calculated

Mailgun is a leading transactional email API service provider targeting developers and businesses that require reliable, scalable email delivery solutions. The company offers a comprehensive suite of email services including sending, validation, optimization, and testing, positioning itself strongly in the technology sector with a large enterprise customer base including major tech companies. The website demonstrates a mature technical infrastructure built on WordPress with modern performance and SEO optimizations, ensuring excellent user experience and accessibility. Security posture is robust with HTTPS enforcement, ISO 27001 certification, and a dedicated security portal, although WHOIS data is unavailable which slightly impacts trust but is mitigated by the company's known parent entity, Sinch. Overall, Mailgun presents a professional, trustworthy, and technically sound platform for transactional email services.

Scanned

NIS2 and GDPR posture

GDPR outside view
95/ 100 · Low
Checks completed
7of 7

NIS2 Art. 21(2)

  1. (a) Risk analysis and security policies: Not visible from outside
  2. (b) Incident handling: One indicator
  3. (c) Business continuity, backups and crisis management: Not visible from outside
  4. (d) Supply chain security: Not visible from outside
  5. (e) Secure acquisition, development and maintenance, including vulnerability handling: Partly checked
  6. (f) Assessing the effectiveness of security measures: Not visible from outside
  7. (g) Cyber hygiene and security training: Not visible from outside
  8. (h) Cryptography and encryption: Partly checked
  9. (i) HR security, access control and asset management: One indicator
  10. (j) Multi-factor authentication and secured communications: Not visible from outside

This scan rated NIS2 with an earlier keyword method that is no longer shown; rescan for the per-article view. Risk management, continuity, supply chain, training, MFA, management oversight (Art. 20) and incident reporting (Art. 23) need internal evidence, and Guard cannot tell whether NIS2 applies to this organisation.

GDPR is indicative only, based on publicly visible signals: Articles 7, 12, 13 and 32 of Regulation (EU) 2016/679 and Article 5(3) of the ePrivacy Directive. Not a certification or legal assessment.

Priority findings

2 findings rated critical or high. Fix these first.

  1. SSL/TLS

    TLS encrypts the connection and proves the site is really yours. Weak or expiring certificates trigger browser warnings and put traffic at risk.

    • High

      Weak Protocols Supported

      Server supports weak protocols: TLSv1.1

      What to do: Disable TLS 1.0, TLS 1.1, and all SSL versions

      • CWE-327
      • OWASP A04:2025
      • ASVS V12.1.1
    • High

      Weak SSL Key Length

      SSL certificate uses 256-bit key, which is considered weak

      What to do: Use at least 2048-bit RSA or 256-bit ECC key

      • CWE-326
      • OWASP A04:2025
      • Mozilla TLS: Mozilla Server Side TLS 6.0 intermediate: rsa_key_size 2048

Need hands-on remediation? Email guard@offseq.com

Keep watching mailgun.com

This scan found 17 issues across 6 checks. Monitoring re-runs those checks daily, emails you when something material changes and records each fix, so you can show progress.

Daily monitoring

Recommended

€25per month

  • TLS certificates and expiry
  • DNS records
  • SPF, DKIM and DMARC
  • Security headers
  • GDPR and NIS2 posture
  • Exposed services
  • Third-party trackers
  • Security score drift

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Results by check

Each check with its score, findings and the evidence it collected.

How this score is calculated

The security score runs 0–100, higher is better. It is the plain average of the security checks that completed in this scan, each counted equally. A check that could not run is left out: it counts neither as a pass nor as a fail.

Counted in this score

SSL/TLS
52
Security headers
85
Email security
80
DNS health
80
Network security
100
GDPR outside view
95
Average
82

Not counted

  • NIS2 outside view: Re-weights evidence from the TLS, email, DNS, network and hygiene checks, so counting it would count that evidence twice. Shown on its own.
  • OffSeq Observations: An AI reading of the site, useful context but not reproducible evidence. Shown on its own.

Findings that cap the score at 49

Each of these is serious on its own, so while any is present the site cannot rate better than high risk, however good the other checks are.

  • The certificate is not trusted by browsers
  • The website is not served over HTTPS
  • A database, remote desktop, file-sharing or Telnet service is reachable from the internet
  • The page loads a script from a compromised source
  • The domain registration has expired
  • SPF authorises every server to send mail as the domain

Partial scans

When the site blocks Guard or most checks cannot run, the score covers only the checks that ran (usually DNS and email), is capped at 75 and is shown as partial, without a risk level.

Risk levels

  • Critical0–25
  • High26–49
  • Medium50–75
  • Low76–100

Breach exposure

Leaked credentials and lookalike domains from OffSeq Breach. The counts are free; the detailed lists are paid add-ons.

Dark web exposure

Add-on

Leaked records that mention mailgun.com, from OffSeq Breach.

Total records
54,702
Employees
6
Customers
54,657
Third parties
39
Weak passwords
9%

Latest record dated 2025-08-19 · 50 subdomains affected

See the 10 newest leaked credentials

A one-off add-on to this report that lists the most recent identifier and password pairs OffSeq Breach holds for mailgun.com.

Select it in the checkout above.

Masked preview

  • –mailgun.com2025-08-19
  • –signup.mailgun.com2025-07-23
  • –mailgun.com2025-06-30
  • –mailgun.com2025-06-30
  • –app.mailgun.com2025-04-15

Breach keeps ingesting new leaks, so these numbers can grow between scans.

Open in Breach(opens in a new tab)Monitor on Breach(opens in a new tab)

Technical appendix

Business context, site observations and technical notes gathered during the scan, and the standards behind each reference.

Business context

Business profile

Mailgun operates a SaaS business model focused on email API services, targeting developers and enterprises needing transactional email capabilities. The company leverages partnerships with related email service providers and maintains a strong ecosystem with comprehensive documentation and support. Its market position is reinforced by a large client base and industry certifications. Revenue streams likely include subscription plans and enterprise contracts. The company is part of Sinch, a larger communications platform provider, enhancing its market credibility and reach. Strategic observations include a focus on customization, deliverability, and compliance, catering to evolving business needs in email communications.

Security posture

Mailgun exhibits a mature security posture with enforced HTTPS, presence of security headers, and ISO 27001 certification. The website links to a security portal and provides incident response contact channels, indicating readiness for security incidents. No obvious vulnerabilities or exposed sensitive data were detected. However, the absence of a security.txt file and explicit incident response page are areas for improvement. Compliance with GDPR is indicated through privacy and cookie policies. Overall, the security culture appears strong but could benefit from enhanced transparency and formal vulnerability disclosure mechanisms.

Recommendations

  1. Publish a security.txt file to facilitate vulnerability reporting and improve transparency.
  2. Create a dedicated incident response page with clear contact information for security issues.
  3. Enhance Content Security Policy headers to further mitigate script-based attacks.
  4. Regularly audit third-party scripts and plugins to avoid vulnerabilities.
  5. Maintain updated WHOIS information or provide justification for privacy protection to improve trust.
Site observations

Automated reading of the public site. Ratings are indicative.

Business

Company
Transactional Email API Service For Developers | Mailgun
Description
Powerful Transactional Email APIs that enable you to send, receive, and track emails, built with developers in mind. Learn more today!
Key services
Send Email API, SMTP Relay, Email Validation API, Email List Validation, Email Template Builder, Email Inbox Placement, Email Deliverability Services, Email Reputation Services, Blocklist Monitoring Services, Email Testing Services
Content quality
excellent
Branding
consistent

Technology

Stack
WordPress, Yoast SEO, WP Rocket, Sinch Core Plugin, Google Fonts (DM Sans), SVG icons
Platforms
WordPress
Performance
fast
Mobile
excellent
Accessibility
good
SEO
excellent

Security

Observed score
85/100
Good practices seen
  • HTTPS enforced
  • Lazy loading and script deferring for performance
  • Security portal linked
  • ISO 27001 certification

Analytics and tracking

Tracking level
minimal
Privacy practices
good

Advertising

Marketing tools
Yoast SEO, WP Rocket
Transparency
good

Site quality

Design
excellent
User experience
excellent
Content relevance
excellent
Navigation
excellent
Professionalism
excellent
Trustworthiness
high

Key observations

  1. Website is fully accessible with no blocking or WAF challenges.
  2. Content is rich, professional, and targeted at developers and businesses.
  3. Strong branding and consistent design.
  4. Multiple external trusted links and partner references.
  5. Good SEO and performance optimizations observed.
  6. WHOIS data unavailable, but website legitimacy supported by business presence and certifications.
Technical notes

Notes

The website is built on WordPress with advanced SEO and performance plugins such as Yoast SEO and WP Rocket, ensuring fast loading times and good SEO rankings. The use of modern web fonts and SVG icons contributes to a polished user interface. Mobile optimization is excellent, and accessibility features are adequately implemented. The technical stack is modern and well-maintained, with no visible technical debt or outdated components. Opportunities exist to further enhance security headers and implement a security.txt file. Hosting provider details are not explicitly identified but the infrastructure supports enterprise-grade performance.
Standards and sources

Reference chips under each finding point to the standard, regulation or specification the finding relates to. They are taken from the official datasets below and mapped conservatively: a finding with no defensible link shows none. NIS2 and GDPR references mark where a finding is relevant evidence, not a compliance verdict. Implementing Regulation (EU) 2024/2690 binds digital infrastructure and digital service providers; for other entities it is the most detailed public reading of the Article 21 measures. WCAG, EN 301 549, European Accessibility Act and Web Accessibility Directive references name the requirement an automated accessibility rule relates to; they are not a conformance verdict.

Retrieved 2026-10-25

Earlier scans of this domain

  1. 82/100 −5Low25 findingsView report
  2. 87/100 −1Low22 findingsView report
  3. 88/100Low21 findingsView report
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