msmtp vs OpenSMTPD
A side-by-side comparison of two self-hosted mail servers options — licensing, setup difficulty, resource needs, and what each one replaces.
| Feature | msmtp | OpenSMTPD |
|---|---|---|
| Deploy effort | Read-the-docs project | Read-the-docs project |
| Health score | 68 · Good | 80 · Excellent |
| Category | Mail Servers | Mail Servers |
| License | GPL-3.0 | ISC |
| Language | C | C |
| Setup difficulty | Easy | Medium |
| Min. RAM | 32 MB | 32 MB |
| Deployment | binary, source | bare-metal, source |
| GitHub stars | ★ 293 | ★ 586 |
| First released | 2004 | 2013 |
| Replaces | Sendmail | Sendmail, Postfix |
What are msmtp and OpenSMTPD?
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
OpenSMTPD
OpenSMTPD is a free implementation of the SMTP protocol developed by the OpenBSD project. It emphasizes simplicity, security, and a readable configuration syntax for running your own mail relay or server.
- Simple configuration
- Security focused
- SMTP relay and delivery
- Filters via extensions
msmtp vs OpenSMTPD: key differences
Both projects are written in C. Licensing differs — GPL-3.0 for msmtp versus ISC for OpenSMTPD. Msmtp is the more established project (first released 2004), while OpenSMTPD arrived in 2013. OpenSMTPD has the considerably larger community, at 586 GitHub stars versus 293.
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 OpenSMTPD if…
- Clean concise config
- Strong security record
Watch out for
- Fewer features than Postfix
- Smaller ecosystem
Frequently asked questions
Is msmtp or OpenSMTPD better?
Neither is universally better. OpenSMTPD has the larger community, while msmtp is simpler to set up (easy difficulty). Choose based on the comparison table above and your own setup.
Are msmtp and OpenSMTPD free and open-source?
Yes. msmtp is licensed under GPL-3.0 and OpenSMTPD under ISC. Both can be self-hosted at no software cost.
Can I run msmtp and OpenSMTPD with Docker?
msmtp: check the project docs for container support. OpenSMTPD: check the project docs for container support.