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rnwood/smtp4dev

smtp4dev - the fake smtp email server for development and testing observed · 2026-08-28

github.com/rnwood/smtp4dev · C# · BSD-3-Clause (permissive) observed · 2026-08-28

Health v2 · maintenance only

90/100

  • Activity 99
  • Release rhythm 73
  • Longevity 100
How is this computed?

round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10) — computed 2026-09-02. Adoption (stars, forks) is never an input.

  • gap_med: 4.5
  • age_days: 5346
  • days_rel: 183
  • days_push: 8
  • n_releases_24m: 19

Full methodology

Adoption not part of the score

3945 stars · 423 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-29, confidence not recorded

smtp4dev is a fake SMTP email server for development and testing, with a web interface, terminal UI, and REST API. It captures outgoing mail from applications so developers can inspect messages without emailing real recipients.

Use cases

  • test email sending locally without spamming real users
  • inspect HTML email rendering and compatibility
  • capture SMTP traffic during integration tests
  • retrieve test emails via IMAP or POP3
  • simulate SMTP errors and TLS scenarios
  • run a disposable mail server in Docker for CI

When to choose

  • you need a full-featured local SMTP catch-all with a web UI
  • you want IMAP/POP3 access, multiple mailboxes, or relay rules in a dev mail server
  • you need cross-platform or Docker-based email testing

When to avoid

  • you need a production mail transfer agent or real mail delivery
  • you only need a minimal catch-all with no UI and prefer a tiny daemon
  • your stack cannot run .NET

Facets

application · maturity active

http-server email testing developer-tools gui terminal-ui developer-tools email testing self-hosted windows cross-platform self-hosted smtp-server fake-smtp email-testing imap pop3 mail-server dotnet web-interface linux macos docker

1 source

Member repositories

RepositoryRoleHealth v2
rnwood/smtp4devmain90

For agents

markdown · JSON · MCP: product_card(name="rnwood/smtp4dev")

Data as of 2026-08-30T08:39:29.467469+00:00 · Report a problem