Postal vs isync
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
isync
IMAP and Maildir mailbox synchronizer
| Feature | Postal | isync |
|---|---|---|
| Category | Mail Servers | Mail Servers |
| License | MIT | GPL-2.0 |
| Language | Ruby | C |
| Setup difficulty | Hard | Medium |
| Min. RAM | 2,048 MB | 32 MB |
| Deployment | docker, bare-metal | binary, source |
| GitHub stars | ★ 16,724 | ★ 400 |
| First released | 2017 | 2000 |
| Replaces | SendGrid, Mailgun, Postmark | Outlook offline mode |
Why pick each one
Choose isync if…
- Released under the GPL-2.0 license
- Written in C
- Tiny footprint — runs in 32 MB RAM
Frequently asked questions
Is Postal or isync better?
Neither is universally better. Postal has the larger community, while isync is simpler to set up (medium difficulty). Choose based on the comparison table above and your own setup.
Are Postal and isync free and open-source?
Yes. Postal is licensed under MIT and isync under GPL-2.0. Both can be self-hosted at no software cost.
Can I run Postal and isync with Docker?
Postal: yes. isync: check the project docs for container support.