Mail-in-a-Box vs smtp4dev
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?
Mail-in-a-Box
Turn a fresh server into a working mail server
VS
smtp4dev
Fake SMTP server for development email testing
| Feature | Mail-in-a-Box | smtp4dev |
|---|---|---|
| Category | Mail Servers | Mail Servers |
| License | CC0-1.0 | GPL-3.0 |
| Language | Python | C# |
| Setup difficulty | Easy | Easy |
| Min. RAM | 1,024 MB | 128 MB |
| Deployment | bare-metal, one-click | docker, binary |
| GitHub stars | ★ 15,385 | ★ 3,941 |
| First released | 2014 | 2015 |
| Replaces | Google Workspace, Microsoft 365 | Mailtrap |
Why pick each one
Frequently asked questions
Is Mail-in-a-Box or smtp4dev better?
Neither is universally better. Mail-in-a-Box has the larger community; both share a easy setup difficulty, so the decision comes down to features and licensing.
Are Mail-in-a-Box and smtp4dev free and open-source?
Yes. Mail-in-a-Box is licensed under CC0-1.0 and smtp4dev under GPL-3.0. Both can be self-hosted at no software cost.
Can I run Mail-in-a-Box and smtp4dev with Docker?
Mail-in-a-Box: check the project docs for container support. smtp4dev: yes.