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Nullmailer

Simple relay-only mail transfer agent

Mail Servers ★ 199 stars Easy setup GPL-2.0

Nullmailer is a minimal mail transfer agent designed only to relay outgoing mail to a smart host. It is ideal for servers and workstations that need to send notifications without running a full MTA.

Official siteSource code

Key features

  • Relay-only operation
  • Tiny footprint
  • Smart host forwarding
  • Queue management

Pros & cons

Strengths

  • Extremely lightweight
  • Simple configuration

Trade-offs

  • Cannot receive mail
  • No local delivery

Is Nullmailer secure?

OSV.dev has no published security advisories for Nullmailer's repository. No known vulnerabilities is not proof of security: it means none have been publicly catalogued.

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

Nullmailer replaces

Self-hosted Sendmail alternatives

Health badge

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SelfHostIndex: 8 · at risk

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The score is recomputed on every nightly rebuild from public repository data — see how it is calculated.

Compare Nullmailer

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