Merge branch 'feat/add-mail-details' into 'master'

feat(mail): add details

See merge request !56

docs/ecolyo/technical/mail.md

@@ -2,14 +2,11 @@
 
 ## Explanation
 
-A templating system was needed for the app. In order to make it easy to use and also responsive, two libraries has been used :
+Two templating libraries are used, they allow easy editing and responsive :
 
-- [Handlebars](https://handlebarsjs.com/)
-- [MJML](https://mjml.io/)
+- [Handlebars](https://handlebarsjs.com/) is used as a semantic template motor. It allow us to split email template in order to reuse some parts (header, footer ...)
 
-Handlebars is used as a semantic template motor. It allow us to split email template in order to reuse some parts (header, footer ...)
-
-Mjml is a lib providing a syntax allowing developers to easily build responsive templates.
+- [MJML](https://mjml.io/) is a lib providing a syntax allowing developers to easily build responsive templates.
 
 ## Usage
 
@@ -77,3 +74,11 @@ const mjml2html = require('mjml-browser')
 ### Useful links
 
 - [Mjml live editor](https://mjml.io/try-it-live/bohYnxKkCq-)
+
+## Bounce token
+
+A bounce token stored in the profile of each user is sent in email. It allows us to track if user clicks on links.
+
+## Unsubscribe
+
+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.