Chatmail Relay vs Session
A side-by-side comparison of two self-hosted chat & communication options — licensing, setup difficulty, resource needs, and what each one replaces.
| Feature | Chatmail Relay | Session |
|---|---|---|
| Deploy effort | Under-an-hour setup | Read-the-docs project |
| Health score | 79 · Good | 80 · Excellent |
| Category | Chat & Communication | Chat & Communication |
| License | MPL-2.0 | GPL-3.0 |
| Language | Python | TypeScript |
| Setup difficulty | Medium | Medium |
| Min. RAM | 512 MB | 256 MB |
| Deployment | docker, bare-metal | bare-metal, binary, source |
| GitHub stars | ★ 484 | ★ 585 |
| First released | 2023 | 2020 |
| Replaces | WhatsApp, Signal | Signal, WhatsApp, Telegram |
What are Chatmail Relay and Session?
Chatmail Relay
A minimal, opinionated mail server configuration optimized to act as a relay for Delta Chat clients, providing instant, encrypted messaging over standard email. It is provisioned automatically for low-maintenance operation.
- Email-based messaging
- Automatic provisioning
- End-to-end encryption
- Low maintenance
Session
Session is an end-to-end encrypted messenger that routes messages through a decentralized onion network of community-operated nodes. It requires no phone number or email to sign up.
- Onion-routed message delivery
- No phone number required
- Decentralized service node network
- End-to-end encryption
Chatmail Relay vs Session: key differences
Chatmail Relay is written in Python, while Session is built with TypeScript. Licensing differs — MPL-2.0 for Chatmail Relay versus GPL-3.0 for Session. Session is the lighter option, starting around 256 MB of RAM against 512 MB for Chatmail Relay. Session is the more established project (first released 2020), while Chatmail Relay arrived in 2023. Chatmail Relay lists first-class Docker deployment; Session does not.
Why pick each one
Choose Chatmail Relay if…
- Uses open email standards
- Hard to censor
Watch out for
- Requires mail server knowledge
- Newer project
Choose Session if…
- Released under the GPL-3.0 license
- Written in TypeScript
- Tiny footprint — runs in 256 MB RAM
Watch out for
- Relies on the Session node network
- Message delivery can be slower
Frequently asked questions
Is Chatmail Relay or Session better?
Neither is universally better. Session has the larger community; both share a medium setup difficulty, so the decision comes down to features and licensing.
Are Chatmail Relay and Session free and open-source?
Yes. Chatmail Relay is licensed under MPL-2.0 and Session under GPL-3.0. Both can be self-hosted at no software cost.
Can I run Chatmail Relay and Session with Docker?
Chatmail Relay: yes. Session: check the project docs for container support.
Which is lighter on resources, Chatmail Relay or Session?
Session has the smaller minimum footprint at 256 MB of RAM, compared to about 512 MB for Chatmail Relay. Real-world usage depends on library size, user count, and enabled features.