email_server: Don't let the My Mail page to blank page

Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: Fioddor Superconcentrado <fioddor@gmail.com>

plinth/modules/email_server/templates/my_mail.html

@@ -23,6 +23,8 @@
         </button>
       </div>
     </form>
+  {% else %}
+    <p>{% trans "Your home directory is ready to receive emails." %}</p>
   {% endif %}
 
   <p>