Compare software

Postal vs OpenSMTPD: catalog facts
Postal	OpenSMTPD
Free Free and open source to run on your own server.	Free Free and open source under the ISC license.
Self-hosted	Linux, Self-hosted, Command line
Self-hosted alternative to hosted transactional email services Handles both sending and receiving mail	Part of the OpenBSD project Simpler than many other SMTP servers
Requires running and maintaining your own mail server Deliverability depends on your own server reputation and setup	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 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.