MailingList.md

@@ -23,6 +23,19 @@ Several mailing lists are hosted on Eurecom's sympa server.
   [\[unsubscribe\]](mailto:sympa@lists.eurecom.fr?subject=unsubscribe openaircn-devel)
   [\[archives\]](http://lists.eurecom.fr/sympa/arc/openaircn-devel)
 
+## How to subscribe or unsubscribe to a mailing list
+
+Clicking on the link `[subscribe]` (or `[unsubscribe]`) above should
+open your email client. You then simply need to send the email.
+
+If clicking the above link does not work, manually send an email to `sympa@lists.eurecom.fr`
+with the subject `subscribe [list name] [your first name] [your last name]`
+(`unsubscribe` instead of `subscribe` to unsubscribe).
+
+`[list name]` is one of `openair5g-user`, `openair5g-devel`, `openaircn-user`,
+`openaircn-devel` depending on which mailing list you want to subscribe
+(or unsubscribe).
+
 ## How to ask questions on the mailing lists
 
 Refer to [this page](AskQuestions).