NixOS Mailserver is a community NixOS module and a simple way to run your own mail server. One declarative configuration sets up mail delivery, mailboxes with IMAP access, spam filtering, DKIM and TLS. You manage accounts, domains, certificates and other options with the rest of the NixOS configuration.

A self-hosted mail server needs a domain and access to its DNS records, a public IP address with configurable reverse DNS (PTR), and reachable port 25/tcp. You will then configure MX, SPF, DKIM and DMARC records according to the project documentation.

NixOS Mailserver publishes a nixos-YY.MM branch for the corresponding NixOS and nixpkgs release. Select your system version in the project's release overview and select the same version in the switcher on Read the Docs. Then follow the current setup guide, which covers adding the module, accounts, certificates and the required DNS records.

Before moving to a new release, read its release notes and any applicable migration instructions.

After deployment, use MXToolbox SuperTool to check the public DNS records, SMTP reachability, reverse DNS and whether the IP address appears on blocklists. This can reveal configuration mistakes that are not visible from the VPS itself.