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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 requiring reliable email delivery, tracking, and optimization. Owned by Sinch, the company serves over 150,000 businesses including major tech firms, positioning itself as a market leader in email infrastructure services. The website demonstrates a mature digital presence with comprehensive product offerings, strong branding, and extensive developer resources. Technically, the site is built on WordPress with modern frameworks and optimized for performance and SEO. Security posture is strong with HTTPS, CSP monitoring, and a dedicated security portal, though explicit incident response contacts and vulnerability disclosures are not publicly visible. Overall, the site is professional, trustworthy, and business-focused, though WHOIS data is unavailable, likely due to privacy protections.

Scanned

This is an earlier scan of mailgun.com. View the latest report

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 providing email APIs and related services to a broad developer and enterprise audience. Its market position is strong, supported by a large client base and integration with Sinch. The company offers a suite of email-related tools including sending, validation, deliverability optimization, and testing. Partnerships with companies like Mailjet and Email on Acid enhance its ecosystem. The website content and navigation reflect a focus on developer usability and enterprise readiness. Revenue streams likely include subscription plans and enterprise contracts. The presence of a security portal and status page indicates operational transparency and customer support maturity.

Security posture

The website employs HTTPS with strong SSL configuration and security headers such as Content Security Policy. It monitors CSP violations and provides a security portal for transparency. No exposed sensitive data or vulnerable libraries were detected in the HTML content. However, the absence of a public incident response contact or vulnerability disclosure program limits full security transparency. GDPR compliance indicators are present via privacy and cookie policies with consent mechanisms. Overall, the security posture is robust but could be improved by publishing explicit incident response and vulnerability disclosure information.

Recommendations

  1. Publish explicit incident response contact information and procedures on the website.
  2. Implement and publicize a vulnerability disclosure policy or security.txt file.
  3. Enhance visible security certifications and compliance badges to increase trust.
  4. Regularly audit third-party scripts and tracking tools to minimize privacy risks.
  5. Maintain updated WHOIS information or provide transparency about privacy protections.
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, Bootstrap, Google Tag Manager, Yoast SEO, WP Rocket, Sinch Core Plugin
Frameworks
Bootstrap
Platforms
WordPress
Performance
fast
Mobile
excellent
Accessibility
good
SEO
excellent

Security

Observed score
85/100
Good practices seen
  • HTTPS enforced
  • Content Security Policy monitoring
  • Security portal available
  • No exposed sensitive data in HTML

Analytics and tracking

Services
Google Tag Manager, Google Analytics (inferred)
Tracking level
moderate
Privacy practices
good

Advertising

Tracking pixels
Google Analytics (inferred)
Marketing tools
Yoast SEO, Sinch Core Plugin
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 rich content and navigation
  2. Strong branding and consistent design
  3. Comprehensive product and solution offerings for transactional email
  4. Multiple external trusted links and partner references
  5. Good SEO and performance optimizations
  6. No visible security or privacy red flags in content
  7. WHOIS data unavailable, limiting domain registration insights
Technical notes

Notes

The website is built on WordPress CMS with Bootstrap framework and uses modern web technologies including lazy loading, preloading fonts, and optimized scripts. Performance optimizations such as WP Rocket caching and minification are in place, contributing to fast load times. SEO is enhanced by Yoast SEO plugin and structured data (JSON-LD) for rich search results. Accessibility and mobile responsiveness are well implemented. No technical debt or deprecated libraries were observed in the provided content. Hosting provider details are not explicit but likely cloud-based given the scale and 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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