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Postfix vs OpenSMTPD: catalog facts
Postfix	OpenSMTPD
Free Free and open source.	Free Free and open source under the ISC license.
macOS, Linux, Self-hosted	Linux, Self-hosted, Command line
Security-focused design Runs on many Unix-like systems	Part of the OpenBSD project Simpler than many other SMTP servers
Transfer agent only; needs a separate IMAP server for mailboxes Configuration requires mail server knowledge	A mail server, not a client for reading email Needs other components for a complete mail setup
Self-hosted	Downloadable app, Self-hosted
Open source	Open source
License not stated	License: ISC
No account needed	No account needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked September 24, 2026	Official website Full listing and sources Checked September 24, 2026

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