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OpenSMTPD

Secure and simple SMTP server from OpenBSD

Mail Servers ★ 586 stars Medium setup ISC

OpenSMTPD is a free implementation of the SMTP protocol developed by the OpenBSD project. It emphasizes simplicity, security, and a readable configuration syntax for running your own mail relay or server.

Official siteSource code

Key features

  • Simple configuration
  • Security focused
  • SMTP relay and delivery
  • Filters via extensions

Pros & cons

Strengths

  • Clean concise config
  • Strong security record

Trade-offs

  • Fewer features than Postfix
  • Smaller ecosystem

Is OpenSMTPD secure?

No known vulnerabilities affect OpenSMTPD's latest release (7.9.0p0). OSV.dev lists 6 past advisories for the project; none of them applies to this release. No known vulnerabilities is not proof of security: it means none have been publicly catalogued.

  • Most recent fixed advisory CVE-2025-62875, published 2025-11-20 (328 days ago)

Source: OSV.dev, checked 2026-10-14. How this is measured.

OpenSMTPD replaces

Self-hosted Sendmail alternativesSelf-hosted Postfix alternatives

Health badge

Maintain OpenSMTPD? Add its health score to your README. The badge links back to this page.

SelfHostIndex: 84 · excellent

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   :alt: SelfHostIndex health score for OpenSMTPD
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The score is recomputed on every nightly rebuild from public repository data — see how it is calculated.

Compare OpenSMTPD

3 head-to-head comparisons.

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