def send_reminders(all_targets):
    """Send reminders for unsent pictures because of internet outage."""
    mail_list = []
    msg = "There are unsent pictures on the Whiteboardbot SD-Card, \
            because of an Internet outage on the last trigger. \
            They are automatically going to get deleted in 30 days."
    for action, activated in all_targets.items():
        if activated:
            if action == 'slack':
                SlackBot.send_message(SlackBot, msg, attachment=None,
                                      channel=get_key("Slack", "channel_name"))
            else:
                mail_list.append(action)
    if len(mail_list) > 0:
        addresses = []
        print(mail_list)
        for mail_num in mail_list:
            addresses.append(get_key(mail_num, "address"))
        # TODO check if this handover worked correctly
        send_reminder(addresses, msg)

    return time()