mail2-nixos-config/nix/sources.json

{
    "nixos-mailserver": {
        "branch": "main",
        "repo": "https://codeberg.org/tokudan/nixos-mailserver.git",
        "rev": "021bc28509ea52895c6834aa9b3e3f460caa0bf9",
        "type": "git"
    }
}