username = "admin";
      fullName = "Administrator";
      passwordFile = "/path/to/password_file";
    };
    mail.outgoing = {
      serverAddress = "smtp.emailprovider.com";
      port = 587;
      username = "user@emailprovider.com";
      passwordFile = "/path/to/smtp_password_file";
    };
    mail.incoming.enable = true;
    secretKeyBaseFile = "/path/to/secret_key_base_file";
  };
}
```

This assumes you have set up an MX record for the address you've
set in [hostname](#opt-services.discourse.hostname) and
requires proper SPF, DKIM and DMARC configuration to be done for
the domain you're sending from, in order for email to be reliably delivered.

If you want to use a different domain for your outgoing email
(for example `example.com` instead of
`discourse.example.com`) you should set
[](#opt-services.discourse.mail.notificationEmailAddress) and
[](#opt-services.discourse.mail.contactEmailAddress) manually.

::: {.note}
Setup of TLS for incoming email is currently only configured
automatically when a regular TLS certificate is used, i.e. when
[](#opt-services.discourse.sslCertificate) and
[](#opt-services.discourse.sslCertificateKey) are
set.
:::

## Additional settings {#module-services-discourse-settings}

Additional site settings and backend settings, for which no
explicit NixOS options are provided,
can be set in [](#opt-services.discourse.siteSettings) and
[](#opt-services.discourse.backendSettings) respectively.

### Site settings {#module-services-discourse-site-settings}

"Site settings" are the settings that can be
changed through the Discourse
UI. Their *default* values can be set using
[](#opt-services.discourse.siteSettings).

Settings are expressed as a Nix attribute set which matches the
structure of the configuration in
[config/site_settings.yml](https://github.com/discourse/discourse/blob/master/config/site_settings.yml).
To find a setting's path, you only need to care about the first
two levels; i.e. its category (e.g. `login`)
and name (e.g. `invite_only`).

Settings containing secret data should be set to an attribute
set containing the attribute `_secret` - a
string pointing to a file containing the value the option
should be set to. See the example.

### Backend settings {#module-services-discourse-backend-settings}

Settings are expressed as a Nix attribute set which matches the
structure of the configuration in
[config/discourse.conf](https://github.com/discourse/discourse/blob/stable/config/discourse_defaults.conf).
Empty parameters can be defined by setting them to
`null`.

### Example {#module-services-discourse-settings-example}

The following example sets the title and description of the
Discourse instance and enables
GitHub login in the site settings,
and changes a few request limits in the backend settings:
```nix
{
  services.discourse = {
    enable = true;
    hostname = "discourse.example.com";
    sslCertificate = "/path/to/ssl_certificate";
    sslCertificateKey = "/path/to/ssl_certificate_key";
    admin = {
      email = "admin@example.com";
      username = "admin";
      fullName = "Administrator";
      passwordFile = "/path/to/password_file";
    };
    mail.outgoing = {
      serverAddress = "smtp.emailprovider.com";
      port = 587;
      username = "user@emailprovider.com";
      passwordFile = "/path/to/smtp_password_file";
    };
    mail.incoming.enable = true;
    siteSettings = {
      required = {
        title = "My Cats";