isync vs OfflineIMAP
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?
isync
IMAP and Maildir mailbox synchronizer
VS
OfflineIMAP
Synchronize IMAP mailboxes to local Maildir
| Feature | isync | OfflineIMAP |
|---|---|---|
| Category | Mail Servers | Mail Servers |
| License | GPL-2.0 | GPL-2.0 |
| Language | C | Python |
| Setup difficulty | Medium | Medium |
| Min. RAM | 32 MB | 64 MB |
| Deployment | binary, source | binary, source |
| GitHub stars | ★ 400 | ★ 631 |
| First released | 2000 | 2002 |
| Replaces | Outlook offline mode | 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
Choose OfflineIMAP if…
- Released under the GPL-2.0 license
- Written in Python
- Tiny footprint — runs in 64 MB RAM
Frequently asked questions
Is isync or OfflineIMAP better?
Neither is universally better. OfflineIMAP has the larger community; both share a medium setup difficulty, so the decision comes down to features and licensing.
Are isync and OfflineIMAP free and open-source?
Yes. isync is licensed under GPL-2.0 and OfflineIMAP under GPL-2.0. Both can be self-hosted at no software cost.
Can I run isync and OfflineIMAP with Docker?
isync: check the project docs for container support. OfflineIMAP: check the project docs for container support.