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Papercut SMTP vs Mailpit: catalog facts
Papercut SMTP	Mailpit
Free Free and open source under the Apache-2.0 licence.	Free Free to download and run.
Windows, Self-hosted	Web, Self-hosted, Command line
Catches test emails without sending them Simple desktop interface for reading captured messages	Single binary or Docker image with no dependencies HTML compatibility, link and spam checks built in
Meant for testing, not a real mail server Desktop app is Windows-only	For testing only, not a real mail client Spam scoring relies on a SpamAssassin setup
Downloadable app, Self-hosted	Downloadable app, Self-hosted
Open source	Open source
License: Apache-2.0	License not stated
No account needed	No account needed
Works offline	Works offline
Official website Full listing and sources Checked October 2, 2026	Official website Full listing and sources Checked September 24, 2026

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