+ // Such a condition may happen if an user:
+ // 1. was mailed the issue,
+ // 2. unsubscribed the newsletter,
+ // 3. subscribed again before the sending was done.
+ // Such a case is reported by mail to people who monitor the website.
+ // If you are reading this comment because of such a mail and the lines above explain what happened,
+ // you only need to reset the state of the issue to "pending".
+ // A cron script will then restart the mailing from where it stopped and only the problematic user will reveive the issue twice.