Postal vs OpenDKIM
A side-by-side comparison of two self-hosted mail servers options — licensing, setup difficulty, resource needs, and what each one replaces.
Not the right match-up?
Postal
Complete mail delivery platform for outgoing email
VS
OpenDKIM
DKIM signing and verification filter for mail servers
| Feature | Postal | OpenDKIM |
|---|---|---|
| Category | Mail Servers | Mail Servers |
| License | MIT | BSD-3-Clause |
| Language | Ruby | C |
| Setup difficulty | Hard | Medium |
| Min. RAM | 2,048 MB | 64 MB |
| Deployment | docker, bare-metal | bare-metal, source |
| GitHub stars | ★ 16,724 | ★ 117 |
| First released | 2017 | 2009 |
| Replaces | SendGrid, Mailgun, Postmark | Proprietary email security gateways |
Why pick each one
Choose OpenDKIM if…
- Released under the BSD-3-Clause license
- Written in C
- Tiny footprint — runs in 64 MB RAM
Frequently asked questions
Is Postal or OpenDKIM better?
Neither is universally better. Postal has the larger community, while OpenDKIM is simpler to set up (medium difficulty). Choose based on the comparison table above and your own setup.
Are Postal and OpenDKIM free and open-source?
Yes. Postal is licensed under MIT and OpenDKIM under BSD-3-Clause. Both can be self-hosted at no software cost.
Can I run Postal and OpenDKIM with Docker?
Postal: yes. OpenDKIM: check the project docs for container support.