Update mail.md

docs/ecolyo/Technical/mail.md

@@ -83,7 +83,14 @@ A bounce token stored in the profile of each user is sent in email. It allows us
 
 A user can unsubscribe to our newsletter by a link in each mails. It **does not** require authentication. This link is built with a `sharecode` token that contains specific permissions to turn off the `sendAnalysisNotification` property in the user profile. The sent link has a TTL of 15 days.
 
-## Mail server
+## Mail worker
+
+From the stack version 1.6, the `mode` needs to be set to `campaign` instead of `noreply`. In local development this might prevent some mails to be received.
+
+- [Jobs documentation](https://docs.cozy.io/en/cozy-stack/workers/#sendmail-worker)
+- [Explaination](https://mattermost.cozycloud.cc/grand-lyon/pl/pirw78phnp8jmpzj8epobupc1r)
+
+## Alpha Mail server
 
 The mail server is configured with the [`cozy.yml` under the mail section](https://github.com/bastiendmt/cozy-stack-compose/blob/main/files/cozy.yml#L36).