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Papercut SMTPsmtp4dev
Free

Free and open source under the Apache-2.0 licence.

 Free

Free to download, with the source code published on GitHub.

Windows, Self-hosted Web, Self-hosted
  • Catches test emails without sending them
  • Simple desktop interface for reading captured messages
  • Captures outgoing email so test messages never reach real inboxes
  • Web interface for inspecting captured messages
  • Meant for testing, not a real mail server
  • Desktop app is Windows-only
  • Meant for development and testing, not for sending real mail
  • Documentation lives mainly in the repository
Downloadable app, Self-hosted Downloadable app, Self-hosted
Open source Closed source
License: Apache-2.0 License not stated
No account needed No account needed
Works offline Works offline

Checked October 2, 2026

Checked October 2, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.