msmtp vs Nullmailer
A side-by-side comparison of two self-hosted mail servers options — licensing, setup difficulty, resource needs, and what each one replaces.
| Feature | msmtp | Nullmailer |
|---|---|---|
| Deploy effort | Read-the-docs project | Read-the-docs project |
| Health score | 68 · Good | 8 · At risk |
| Category | Mail Servers | Mail Servers |
| License | GPL-3.0 | GPL-2.0 |
| Language | C | C++ |
| Setup difficulty | Easy | Easy |
| Min. RAM | 32 MB | 16 MB |
| Deployment | binary, source | bare-metal, source |
| GitHub stars | ★ 293 | ★ 199 |
| First released | 2004 | 2000 |
| Replaces | Sendmail | Sendmail |
What are msmtp and Nullmailer?
msmtp
msmtp is a small SMTP client that acts as an SMTP relay for command-line tools and mail user agents, forwarding messages to a real mail server. It supports TLS, authentication, and multiple account profiles.
- SMTP relay client
- TLS and authentication
- Multiple account profiles
- Sendmail-compatible mode
Nullmailer
Nullmailer is a minimal mail transfer agent designed only to relay outgoing mail to a smart host. It is ideal for servers and workstations that need to send notifications without running a full MTA.
- Relay-only operation
- Tiny footprint
- Smart host forwarding
- Queue management
msmtp vs Nullmailer: key differences
Msmtp is written in C, while Nullmailer is built with C++. Licensing differs — GPL-3.0 for msmtp versus GPL-2.0 for Nullmailer. Nullmailer is the lighter option, starting around 16 MB of RAM against 32 MB for msmtp. Nullmailer is the more established project (first released 2000), while msmtp arrived in 2004.
Why pick each one
Choose msmtp if…
- Released under the GPL-3.0 license
- Easy to set up — beginner-friendly
- Written in C
- Tiny footprint — runs in 32 MB RAM
Choose Nullmailer if…
- Extremely lightweight
- Simple configuration
Watch out for
- Cannot receive mail
- No local delivery
Frequently asked questions
Is msmtp or Nullmailer better?
Neither is universally better. msmtp has the larger community; both share a easy setup difficulty, so the decision comes down to features and licensing.
Are msmtp and Nullmailer free and open-source?
Yes. msmtp is licensed under GPL-3.0 and Nullmailer under GPL-2.0. Both can be self-hosted at no software cost.
Can I run msmtp and Nullmailer with Docker?
msmtp: check the project docs for container support. Nullmailer: check the project docs for container support.
Which is lighter on resources, msmtp or Nullmailer?
Nullmailer has the smaller minimum footprint at 16 MB of RAM, compared to about 32 MB for msmtp. Real-world usage depends on library size, user count, and enabled features.