Guide · Open source
How to use Postal: install and run the open source mail server
Updated · written with AI from the project's own documentation and checked against our catalogue data
Postal is an open source mail server that you run on your own machines, meant for websites and web servers that need to send and receive email. This guide explains what it is, how to get the code, and where to find the full setup documentation. By the end you will know the basic install path and which parts of the job need careful planning.
Postalpostalserver/postal · ★ 16.9k · MIT Install options & downloads Quick start
- 1Read the docs first. Open the installation instructions at docs.postalserver.io/getting-started to confirm the requirements.
- 2Install Ruby. Install the Ruby version the installation docs specify for Postal.
- 3Clone the repository. Run git clone https://github.com/postalserver/postal to get the source code.
- 4Build and configure. Follow the build and configuration steps in the official installation guide.
- 5Plan DNS and security. Set up the DNS records and server security needed for reliable sending and receiving.
What is Postal and who is it for?
Postal describes itself as a complete and fully featured mail server for websites and web servers. The project positions it as a self-hosted alternative to hosted services such as Sendgrid, Mailgun or Postmark, so you run the software on your own servers instead of paying a third party to send mail for you.
It suits teams that want their own transactional email infrastructure, developers who send email from a web application and prefer self-hosting, and organisations that want mail data kept on servers they control. Ruby developers who want to read or change the code will also find it useful.
What do you need before you install Postal?
The install method is clone-and-build, and the main prerequisite named in the source is Ruby. The installation docs list the Ruby version required, so check them before you start.
Running a mail server also involves DNS, IP reputation and security setup. If you have no server administration experience, expect this to be the hard part, not the code.
- Ruby (check the installation docs for the required version)
- A server you control where you can manage DNS records
- Git, to clone the repository
How do you get the Postal code?
Start by cloning the repository from GitHub. The README gives this command.
After cloning, follow the installation instructions in the official docs, which cover building and configuring the server.
git clone https://github.com/postalserver/postalWhere do you find the full setup instructions?
The README links to the main documentation, a getting-started guide with installation instructions, and pages covering FAQs and the feature list. Use these as the source of truth for configuration steps, since this page only covers the basic path.
If you get stuck, the README points to GitHub Discussions for questions and feature requests, and to a Discord server for chat.
- Documentation: docs.postalserver.io
- Installation instructions: docs.postalserver.io/getting-started
- FAQs and feature list: docs.postalserver.io/welcome/faqs and docs.postalserver.io/welcome/feature-list
- Help: GitHub Discussions and the Discord server linked from the README
What should you consider before running Postal in production?
Postal handles both incoming and outgoing email, so you are responsible for the mail path end to end. Plan for DNS configuration, sender reputation and server security before you send real messages.
If a hosted service is enough for your volume, it is simpler. Self-hosting makes sense when keeping control of the infrastructure is worth the operational work.
- Confirm your Ruby version against the installation docs
- Plan DNS records and IP reputation
- Review the security guidance in the documentation
What people use it for
- Sending transactional email, such as password resets, from a web application
- Receiving and handling incoming email for a website you run
- Keeping customer mail data on servers you control
- Reading or modifying mail server code as a Ruby developer
Frequently asked questions
Is Postal free to use?
Postal is released under the MIT licence, which the project lists on its repository. You can run and modify it under those terms. Your hosting and operational costs still apply.
What do I need to run Postal?
The main prerequisite named in the source is Ruby, and the installation docs give the required version. You also need a server you control and enough administration experience to handle DNS, IP reputation and security.
How do I install Postal?
Clone the repository with git clone https://github.com/postalserver/postal, then follow the installation instructions at docs.postalserver.io/getting-started. The install is a clone-and-build process.
Is Postal an alternative to Sendgrid or Mailgun?
The README describes Postal as a self-hosted alternative to Sendgrid, Mailgun and Postmark. Instead of sending through a hosted provider, you run the mail server yourself.
How does Postal compare to Mailu or Postfix?
Comparable projects include Mailu, Mail-in-a-Box, Haraka and Postfix. The source does not compare their features, so review each project's documentation against your needs before choosing.
Where can I get help if something breaks?
Use the FAQs in the official docs, ask in GitHub Discussions, or join the Discord server linked from the README.
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Our verdict
Postal suits teams and Ruby developers who want to run their own sending and receiving infrastructure and are comfortable with DNS, reputation and security work. If you only send a few emails or lack server administration experience, a hosted service like Sendgrid, Mailgun or Postmark is the simpler choice, and a desktop email client is the wrong tool entirely.
Install options & downloads