docs: some more info on DKIM / SPF (#371)

.github/labeler.yml

@@ -12,3 +12,8 @@ postmortems:
 argilla:
 - changed-files:
   - any-glob-to-any-file: 'docker/argilla/docker-compose.yml'
+
+📨 email:
+- changed-files:
+  - any-glob-to-any-file: 'docs/mail.md'
+  - any-glob-to-any-file: 'confs/common/systemd/system/[email protected]'

docs/mail.md

@@ -2,6 +2,11 @@
 
 Because mail is difficult to setup, we use [Proxmox Mail Gateway](https://www.proxmox.com/en/proxmox-mail-gateway) as a relay to all servers. It ensure correct SPF, but also it adds DKIM signature.
 
+The DKIM and spf records are configured on main domain *openfoodfacts.org*.
+
+While DKIM is specific (because Brevo and Google keys are distinct by construction), 
+main SPF rule includes brevo and google servers.
+
 No server receive mail, but they should be able to send them.
 
 <a id="only-domain"></a>
@@ -16,12 +21,16 @@ We use Gmail for email boxes and groups.
 We have a DKIM record configured for google domain and sub-domains in the DNS, we also take into account in SPF rule.
 You can find the public key in google workspace admin console, under gmail.
 
+
 ## Brevo
 
 We use Brevo to send newsletters.
 
 We have a DKIM record configured for the Brevo domain in the DNS, we also take into account in SPF rule.
-You can find the public key if you are logged as admin in Brevo.
+They use the **hello.openfoodfacts.org** subdomain.
+
+You can find the public key if you are logged as admin in Brevo, in the top right corner menu, going in "Senders, domains and dedicated IPs".
+Clicking on domains, and then the hello.openfoodfacts.org domain, you can see the needed DNS records. 
 
 ## Proxmox Mail Gateway
 
@@ -206,4 +215,4 @@ If you do not receive the email on expected group, here are some checks:
 
 * [Debian reference](https://www.debian.org/doc/manuals/debian-reference/ch06.en.html#_the_mail_system)
 * [Debian wiki Postfix](https://wiki.debian.org/Postfix)
-* [Debian wiki Exim](https://wiki.debian.org/Exim)
+* [Debian wiki Exim](https://wiki.debian.org/Exim)