[DOC] add todo about reloading mails after odoo starts to get undelivered mails

mailgun/README.rst

@@ -7,6 +7,10 @@ There is no IMAP or POP3 servers on mailgun that is to be used with odoo.
 That is why we need this module. It fetches messages from mailgun using their API
 and stores them in odoo.
 
+TODO.
+
+* If emails are sent when odoo is stopped then Mailgun will retry (other than for delivery notification) during 8 hours at the following intervals before stop trying: 10 minutes, 10 minutes, 15 minutes, 30 minutes, 1 hour, 2 hour and 4 hours. This could be fixed by fetching undelivered messages after odoo starts.
+
 Credits
 =======
 

mailgun/doc/index.rst

@@ -50,8 +50,6 @@ Usage
 * Open ``Discuss`` in odoo
 * See your message there
 * Reply to the message and check it in your mail client (e.g. gmail.com)
-* Stop odoo and send several emails again. On odoo starting you see all your messages in ``Discuss``
-