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OpenSMTPD vs Mox: catalog facts
OpenSMTPD	Mox
Free Free and open source under the ISC license.	Free Free and open source.
Linux, Self-hosted, Command line	Linux, Self-hosted
Part of the OpenBSD project Simpler than many other SMTP servers	Single program covering SMTP, IMAP and webmail Built-in DKIM, SPF, DMARC, MTA-STS and DANE
A mail server, not a client for reading email Needs other components for a complete mail setup	Younger and less widely deployed than Postfix and Dovecot Deliverability still depends on your IP reputation and DNS
Downloadable app, Self-hosted	Self-hosted
Open source	Open source
License: ISC	License not stated
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.