Python EmailMultiAlternations不发送密件抄送电子邮件

我有一个Django管理命令，定义如下：

class Command(BaseCommand):
    help = "Sends out an email with new jobs added in a timespan of a week"

    def handle(self, *args, **options):
        time_a_week_ago = timezone.now() - timedelta(days=7)
        time_now = timezone.now()
        job_listings_added_this_week = JobListing.objects.filter(time_added__gte=time_a_week_ago, time_added__lt=time_now)
        email_subscribers = EmailSubscriber.objects.all()
        emails = []
        for subscriber in email_subscribers:
            emails.append(subscriber.email)
        msg_plain = render_to_string("employers/weekly_newsletter.txt", {"joblistings_list": job_listings_added_this_week})
        msg_html = render_to_string("employers/weekly_newsletter.html", {"joblistings_list": job_listings_added_this_week})

        msg = EmailMultiAlternatives("New jobs added this week", msg_plain, "newsletter@myjobboard.com", [],  bcc=[emails])
        msg.attach_alternative(msg_html, "text/html")
        msg.send()

        self.stdout.write(self.style.SUCCESS("Successfuly sent out the weekly email."))

我将电子邮件内容设置为输出到文件。当我运行管理命令时，我得到的是：

Content-Type: multipart/alternative;
 boundary="===============8145459042862347861=="
MIME-Version: 1.0
Subject: New jobs added this week
From: newsletter@myjobboard.com
Date: Thu, 12 Nov 2020 05:23:05 -0000
Message-ID: 
 <160512424922.55295.17004148678390675586@johns-computer.168.1.22>

--===============8145459042862347861==
Content-Type: text/plain; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit

Jobs added last week
Hey! These job listings were added last week:

    Test job 5 - click here: http://127.0.0.1:8000/12/

    Test job 6 - click here: http://127.0.0.1:8000/13/


--===============8145459042862347861==
Content-Type: text/html; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit

<h1> Jobs added last week </h1>

    <p> Hey! These job listings were added last week: </p>
    <ul>
    
        <li><a href="http://127.0.0.1:8000/12/">Test job 5</a></li>
    
        <li><a href="http://127.0.0.1:8000/13/">Test job 6</a></li>
    
    </ul>


--===============8145459042862347861==--

-------------------------------------------------------------------------------

内容类型：多部分/备选；
边界=“======================8145459042862347861==”
MIME版本：1.0
主题：本周新增就业岗位
发件人：newsletter@myjobboard.com
日期：2020年11月12日星期四05:23:05-0000
消息ID:
--===============8145459042862347861==
内容类型：文本/纯文本；charset=“utf-8”
MIME版本：1.0
内容传输编码：7bit
上周增加的工作
嘿上周添加了以下工作列表：
测试作业5-单击此处：http://127.0.0.1:8000/12/
测试作业6-单击此处：http://127.0.0.1:8000/13/
--===============8145459042862347861==
内容类型：text/html；charset=“utf-8”
MIME版本：1.0
内容传输编码：7bit
上周增加的工作
嘿！上周添加了以下工作列表：





--===============8145459042862347861==--
-------------------------------------------------------------------------------

---

在电子邮件标题中，我没有看到密件抄送。为什么呢为什么我的EmailMultiAlternatives不包括密件抄送邮件头？

尝试将

Bcc=[emails]

更改为

Bcc=emails

由于

电子邮件

已经是一个列表，因此不需要额外的方括号