虽然 Python 通过 smtplib 模块提供了邮件发送的接口，但是 Django 在其基础上提供了更简化的支持。这些封装意在加快邮件发送，在开发时测试发送邮件，在不支持 SMTP 的平台上支持发送邮件。
这些代码位于 django.core.mail 模块。
使用 send_mail() 进行简单的邮件发送。例如，发送纯文本消息：
from django.core.mail import send_mail\n\nsend_mail(\n "Subject here",\n "Here is the message.",\n "from@example.com",\n ["to@example.com"],\n fail_silently=False,\n)\n当需要额外的邮件发送功能时，使用 EmailMessage 或 EmailMultiAlternatives。例如，发送包含 HTML 和纯文本版本的多部分邮件，使用特定模板和自定义标头，可以采用以下方法：
from django.core.mail import EmailMultiAlternatives\nfrom django.template.loader import render_to_string\n\n# First, render the plain text content.\ntext_content = render_to_string(\n "templates/emails/my_email.txt",\n context={"my_variable": 42},\n)\n\n# Secondly, render the HTML content.\nhtml_content = render_to_string(\n "templates/emails/my_email.html",\n context={"my_variable": 42},\n)\n\n# Then, create a multipart email instance.\nmsg = EmailMultiAlternatives(\n subject="Subject here",\n body=text_content,\n from_email="from@example.com",\n to=["to@example.com"],\n headers={"List-Unsubscribe": "<mailto:unsub@example.com>"},\n)\n\n# Lastly, attach the HTML content to the email instance and send.\nmsg.attach_alternative(html_content, "text/html")\nmsg.send()\n邮件是通过 SMTP 主机和端口发送的，由配置项 EMAIL_HOST 和 EMAIL_PORT 指定。如果配置了 EMAIL_HOST_USER 和 EMAIL_HOST_PASSWORD ，那么它们将被用来验证 SMTP 服务器。配置项 EMAIL_USE_TLS 和 EMAIL_USE_SSL 控制是否使用安全连接。
send_mail()Link to this heading#在大多数情况里，你可以使用 django.core.mail.send_mail() 来发送邮件。
参数 subject, message, from_email 和 recipient_list 是必须的。
subject: 一个字符串。
message: 一个字符串。
from_email ：字符串。如果为 None ，Django 将使用 DEFAULT_FROM_EMAIL 设置的值。
recipient_list: 一个字符串列表，每项都是一个邮箱地址。recipient_list 中的每个成员都可以在邮件的 "收件人:" 中看到其他的收件人。
The following parameters are optional, and must be given as keyword arguments\nif used.
\nfail_silently: 一个布尔值。若为 False， send_mail() 会在发生错误时抛出 smtplib.SMTPException 。可在 smtplib 文档找到一系列可能的异常，它们都是 SMTPException 的子类。
auth_user: 可选的用户名，用于验证登陆 SMTP 服务器。 若未提供，Django 会使用 EMAIL_HOST_USER 指定的值。
auth_password: 可选的密码，用于验证登陆 SMTP 服务器。若未提供， Django 会使用 EMAIL_HOST_PASSWORD 指定的值。
connection: 可选参数，发送邮件使用的后端。若未指定，则使用默认的后端。查询 邮件后端 文档获取更多细节。
html_message: 若提供了 html_message，会使邮件成为 multipart/alternative 的实例， message 的内容类型则是 text/plain ，并且 html_message 的内容类型是 text/html 。
返回值会是成功发送的信息的数量（只能是 0 或 1 ，因为同时只能发送一条消息）。
send_mass_mail()Link to this heading#django.core.mail.send_mass_mail() 用于批量发送邮件。
datatuple 是一个元组，形式如下:
(subject, message, from_email, recipient_list)\nfail_silently, auth_user, auth_password and connection have the\nsame functions as in send_mail(). They must be given as keyword arguments\nif used.
Each separate element of datatuple results in a separate email message.\nAs in send_mail(), recipients in the same recipient_list will all see\nthe other addresses in the email messages' "To:" field.
举个例子，以下代码会向两个不同的收件人列表发送两封不同的邮件，却复用了同一条连接:
\nmessage1 = (\n "Subject here",\n "Here is the message",\n "from@example.com",\n ["first@example.com", "other@example.com"],\n)\nmessage2 = (\n "Another Subject",\n "Here is another message",\n "from@example.com",\n ["second@test.com"],\n)\nsend_mass_mail((message1, message2), fail_silently=False)\n返回值是成功发送的消息的数量。
\n\nsend_mass_mail() vs. send_mail()Link to this heading#The main difference between send_mass_mail() and send_mail() is\nthat send_mail() opens a connection to the mail server each time it's\nexecuted, while send_mass_mail() uses a single connection for all of its\nmessages. This makes send_mass_mail() slightly more efficient.
mail_admins()Link to this heading#django.core.mail.mail_admins() 是定义在 ADMINS 配置项中，用于向网站所有者快速发送邮件。
mail_admins() 在主题前面添加 EMAIL_SUBJECT_PREFIX 指定的前缀，默认是 "[Django] " 。
邮件头的 "发件人:" 由 SERVER_EMAIL 配置项指定。
创建这个方法是为了方便和可读性。
\n若提供了 html_message，会使邮件成为 multipart/alternative 的实例， message 的内容类型则是 text/plain ，并且 html_message 的内容类型是 text/html 。
mail_managers()Link to this heading#django.core.mail.mail_managers() 类似 mail_admins()，但它向 MANAGERS 指定的管理员们发送邮件。
以下发送了一封邮件给 john@example.com 和 jane@example.com，他们都出现在 "收件人:":
\nsend_mail(\n "Subject",\n "Message.",\n "from@example.com",\n ["john@example.com", "jane@example.com"],\n)\nThis sends a message to john@example.com and jane@example.com, with\nthem both receiving a separate email:
datatuple = (\n ("Subject", "Message.", "from@example.com", ["john@example.com"]),\n ("Subject", "Message.", "from@example.com", ["jane@example.com"]),\n)\nsend_mass_mail(datatuple)\nHeader injection 是一个开发漏洞，攻击者可以利用它在邮件头插入额外信息，以控制脚本生成的邮件中的 "收件人:" 和 "发件人:" 内容。
\nThe Django email functions outlined above all protect against header injection\nby forbidding newlines in header values. If any subject, from_email or\nrecipient_list contains a newline (in either Unix, Windows or Mac style),\nthe email function (e.g. send_mail()) will raise ValueError and,\nhence, will not send the email. It's your responsibility to validate all data\nbefore passing it to the email functions.
如果邮件的 内容 的开始部分包含了邮件头信息，这些头信息只会作为邮件内容原样打印。
Here's an example view that takes a subject, message and from_email\nfrom the request's POST data, sends that to admin@example.com and redirects\nto "/contact/thanks/" when it's done:
from django.core.mail import send_mail\nfrom django.http import HttpResponse, HttpResponseRedirect\n\n\ndef send_email(request):\n subject = request.POST.get("subject", "")\n message = request.POST.get("message", "")\n from_email = request.POST.get("from_email", "")\n if subject and message and from_email:\n try:\n send_mail(subject, message, from_email, ["admin@example.com"])\n except ValueError:\n return HttpResponse("Invalid header found.")\n return HttpResponseRedirect("/contact/thanks/")\n else:\n # In reality we'd use a form class\n # to get proper validation errors.\n return HttpResponse("Make sure all fields are entered and valid.")\nEmailMessage 类Link to this heading#Django's send_mail() and send_mass_mail() functions are actually\nthin wrappers that make use of the EmailMessage class.
Not all features of the EmailMessage class are available through the\nsend_mail() and related wrapper functions. If you wish to use advanced\nfeatures, such as BCC'ed recipients, file attachments, or multi-part email,\nyou'll need to create EmailMessage instances directly.
EmailMessage is responsible for creating the email message itself. The\nemail backend is then responsible for sending the\nemail.
For convenience, EmailMessage provides a send()\nmethod for sending a single email. If you need to send multiple messages, the\nemail backend API provides an alternative.
EmailMessage 对象Link to this heading#The EmailMessage class is initialized with the following\nparameters. All parameters are optional and can be set at any time prior\nto calling the send() method.
The first four parameters can be passed as positional or keyword arguments,\nbut must be in the given order if positional arguments are used:
\nsubject: 邮件的主题。
body: 邮件内容，需要为纯文本格式。
from_email: 发件人地址。 fred@example.com 和 Fred <fred@example.com> 形式都是合法的。若省略，则使用 DEFAULT_FROM_EMAIL 配置的值。
to: 一个包含收件人地址的列表或元组。
The following parameters must be given as keyword arguments if used:
\ncc: 一个包含收件人地址的列表或元组，指定“抄送”对象。
bcc: 一个包含地址的列表或元组，指定“密送”对象。
reply_to: 一个包含收件人地址的列表或元组，指定“回复”对象。
attachments: A list of attachments to put on the message. Each can\nbe an instance of MIMEPart or\nEmailAttachment, or a tuple with attributes\n(filename, content, mimetype).
headers: 一个字典，包含邮件中额外的头信息。字典的关键字是头的名称，值为头的值。需要由调用者确保头名和值的正确性。对应的属性是 extra_headers 。
connection: An email backend instance.\nUse this parameter if you are sending the EmailMessage via\nsend() and you want to use the same connection for multiple\nmessages. If omitted, a new connection is created when send() is\ncalled. This parameter is ignored when using\nsend_messages().
例如：
\nfrom django.core.mail import EmailMessage\n\nemail = EmailMessage(\n subject="Hello",\n body="Body goes here",\n from_email="from@example.com",\n to=["to1@example.com", "to2@example.com"],\n bcc=["bcc@example.com"],\n reply_to=["another@example.com"],\n headers={"Message-ID": "foo"},\n)\n这个类拥有以下方法：
\nSends the message. If a connection was specified when the email was\nconstructed, that connection will be used. Otherwise, an instance of\nthe default backend will be instantiated and used. If the keyword\nargument fail_silently is True, exceptions raised while sending\nthe message will be quashed. An empty list of recipients will not raise\nan exception. It will return 1 if the message was sent\nsuccessfully, otherwise 0.
Constructs and returns a Python email.message.EmailMessage\nobject representing the message to be sent.
The keyword argument policy allows specifying the set of rules for\nupdating and serializing the representation of the message. It must be\nan email.policy.Policy object. Defaults to\nemail.policy.default. In certain cases you may want to use\nSMTP, SMTPUTF8 or a custom\npolicy. For example,\ndjango.core.mail.backends.smtp.EmailBackend uses the\nSMTP policy to ensure \\r\\n line endings as\nrequired by the SMTP protocol.
If you ever need to extend Django's EmailMessage class,\nyou'll probably want to override this method to put the content you\nwant into the Python EmailMessage object.
Returns a list of all the recipients of the message, whether they're\nrecorded in the to, cc or bcc attributes. This is another\nmethod you might need to override when subclassing, because the SMTP\nserver needs to be told the full list of recipients when the message\nis sent. If you add another way to specify recipients in your class,\nthey need to be returned from this method as well.
Creates a new attachment and adds it to the message. There are two ways\nto call attach():
You can pass it three arguments: filename, content and\nmimetype. filename is the name of the file attachment as it\nwill appear in the email, content is the data that will be\ncontained inside the attachment and mimetype is the optional MIME\ntype for the attachment. If you omit mimetype, the MIME content\ntype will be guessed from the filename of the attachment.
例如：
\nmessage.attach("design.png", img_data, "image/png")\nIf you specify a mimetype of message/rfc822,\ncontent can be a django.core.mail.EmailMessage or\nPython's email.message.EmailMessage or\nemail.message.Message.
对于以 text/ 开头的 mimetype 类型，其内容应该是字符串。二进制数据将尝试以 UTF-8 解码，如果失败了，MIME 类型会被改为 application/octet-stream ，并不会修改数据内容。
Or for attachments requiring additional headers or parameters, you\ncan pass attach() a single Python\nMIMEPart object. This will be attached\ndirectly to the resulting message. For example, to attach an inline\nimage with a Content-ID:
import email.utils\nfrom email.message import MIMEPart\nfrom django.core.mail import EmailMultiAlternatives\n\nmessage = EmailMultiAlternatives(...)\nimage_data_bytes = ... # Load image as bytes\n\n# Create a random Content-ID, including angle brackets\ncid = email.utils.make_msgid()\ninline_image = email.message.MIMEPart()\ninline_image.set_content(\n image_data_bytes,\n maintype="image",\n subtype="png", # or "jpeg", etc. depending on the image type\n disposition="inline",\n cid=cid,\n)\nmessage.attach(inline_image)\n# Refer to Content-ID in HTML without angle brackets\nmessage.attach_alternative(f'… <img src="cid:{cid[1:-1]}"> …', "text/html")\nPython's email.contentmanager.set_content() documentation\ndescribes the supported arguments for MIMEPart.set_content().
Creates a new attachment using a file from your filesystem. Call it\nwith the path of the file to attach and, optionally, the MIME type to\nuse for the attachment. If the MIME type is omitted, it will be guessed\nfrom the filename. You can use it like this:
\nmessage.attach_file("/images/weather_map.png")\nFor MIME types starting with text/, binary data is handled\nas in attach().
A named tuple to store attachments to an email.
\nThe named tuple has the following indexes:
\nfilename
content
mimetype
It can be useful to include multiple versions of the content in an email; the\nclassic example is to send both text and HTML versions of a message. With\nDjango's email library, you can do this using the\nEmailMultiAlternatives class.
A subclass of EmailMessage that allows additional versions of the\nmessage body in the email via the attach_alternative() method. This\ndirectly inherits all methods (including the class initialization) from\nEmailMessage.
A list of EmailAlternative named tuples.\nThis is particularly useful in tests:
self.assertEqual(len(msg.alternatives), 1)\nself.assertEqual(msg.alternatives[0].content, html_content)\nself.assertEqual(msg.alternatives[0].mimetype, "text/html")\nAlternatives should only be added using the attach_alternative()\nmethod, or passed to the constructor.
在电子邮件中附加消息正文的替代表示。
\n例如，要发送文本和 HTML 组合，你可以这样写：
\nfrom django.core.mail import EmailMultiAlternatives\n\nsubject = "hello"\nfrom_email = "from@example.com"\nto = "to@example.com"\ntext_content = "This is an important message."\nhtml_content = "<p>This is an <strong>important</strong> message.</p>"\nmsg = EmailMultiAlternatives(subject, text_content, from_email, [to])\nmsg.attach_alternative(html_content, "text/html")\nmsg.send()\nReturns a boolean indicating whether the provided text is\ncontained in the email body and in all attached MIME type\ntext/* alternatives.
This can be useful when testing emails. For example:
\ndef test_contains_email_content(self):\n subject = "Hello World"\n from_email = "from@example.com"\n to = "to@example.com"\n msg = EmailMultiAlternatives(subject, "I am content.", from_email, [to])\n msg.attach_alternative("<p>I am content.</p>", "text/html")\n\n self.assertIs(msg.body_contains("I am content"), True)\n self.assertIs(msg.body_contains("<p>I am content.</p>"), False)\nA named tuple to store alternative versions of email content.
\nThe named tuple has the following indexes:
\ncontent
mimetype
By default, the MIME type of the body parameter in an EmailMessage\nis "text/plain". It is good practice to leave this alone, because it\nguarantees that any recipient will be able to read the email, regardless of\ntheir mail client. However, if you are confident that your recipients can\nhandle an alternative content type, you can use the content_subtype\nattribute on the EmailMessage class to change the main content type.\nThe major type will always be "text", but you can change the subtype. For\nexample:
msg = EmailMessage(subject, html_content, from_email, [to])\nmsg.content_subtype = "html" # Main content is now text/html\nmsg.send()\n发送邮件的动作是由邮件后端执行的。
\n邮件后端类拥有以下方法：
\nopen() 创建一个发送邮件的长连接。
close() 关闭当前发送邮件的连接。
send_messages(email_messages) sends a list of EmailMessage\nobjects. If the connection is not open, this call will implicitly open the\nconnection, and close the connection afterward. If the connection is already\nopen, it will be left open after mail has been sent.
这也可以用作内容管理器，它会在需要的时候自动调用 open() 和 close():
from django.core import mail\n\nwith mail.get_connection() as connection:\n mail.EmailMessage(\n subject1,\n body1,\n from1,\n [to1],\n connection=connection,\n ).send()\n mail.EmailMessage(\n subject2,\n body2,\n from2,\n [to2],\n connection=connection,\n ).send()\nThe get_connection() function in django.core.mail returns an\ninstance of the email backend that you can use.
默认情况下，调用 get_connection() 会返回配置项 EMAIL_BACKEND 指定的后端。如果你传入了 backend 参数，将会返回该后端的实例。
The keyword-only fail_silently argument controls how the backend should\nhandle errors. If fail_silently is True, exceptions during the email\nsending process will be silently ignored.
All other keyword arguments are passed directly to the constructor of the\nemail backend.
\nDjango 自带了几种邮件后端。除了 SMTP 后端（默认值）外，这些后端应仅在开发和测试阶段使用。如果对发送邮件有特殊的需求，你可以 编写自定义后端。
\n\n这是默认的后端。邮件将会通过 SMTP 服务器发送。
\n若以下某个参数值为 None，则会从匹配的设置项中读取：
host: EMAIL_HOST
port: EMAIL_PORT
username: EMAIL_HOST_USER
password: EMAIL_HOST_PASSWORD
use_tls: EMAIL_USE_TLS
use_ssl: EMAIL_USE_SSL
timeout: EMAIL_TIMEOUT
ssl_keyfile: EMAIL_SSL_KEYFILE
ssl_certfile: EMAIL_SSL_CERTFILE
SMTP 后端是 Django 默认配置的。如果你想显示的指定，将以下内容放入你的配置中：
\nEMAIL_BACKEND = "django.core.mail.backends.smtp.EmailBackend"\nIf unspecified, the default timeout will be the one provided by\nsocket.getdefaulttimeout(), which defaults to None (no timeout).
控制台后端仅将邮件发送至标准输出，而不是真的发送。默认情况下，控制台后端输出至 stdout。在创建连接时，你可以提供 stream 关键字参数来使用另一个类似 stream 的对象。
为了使用该后端，将以下代码加入你的配置中：
\nEMAIL_BACKEND = "django.core.mail.backends.console.EmailBackend"\n该后端不是为了在生产环境使用的——出于方便的目的，让你在开发阶段使用。
\nThe file backend writes emails to a file. A new file is created for each new\nsession that is opened on this backend. The directory to which the files are\nwritten is either taken from the EMAIL_FILE_PATH setting or from the\nfile_path keyword when creating a connection with get_connection().
为了使用该后端，将以下代码加入你的配置中：
\nEMAIL_BACKEND = "django.core.mail.backends.filebased.EmailBackend"\nEMAIL_FILE_PATH = "/tmp/app-messages" # change this to a proper location\n该后端不是为了在生产环境使用的——出于方便的目的，让你在开发阶段使用。
\nThe 'locmem' backend stores messages in a special attribute of the\ndjango.core.mail module. The outbox attribute is created when the first\nmessage is sent. It's a list with an EmailMessage instance for each\nmessage that would be sent.
为了使用该后端，将以下代码加入你的配置中：
\nEMAIL_BACKEND = "django.core.mail.backends.locmem.EmailBackend"\n该后端不是为了在生产环境使用的——出于方便的目的，让你在开发阶段使用。
\nDjango 的测试器 自动为测试使用这个后端。
\n就像该后端的名字表示的一样，该后端对你发送的消息什么也不做。指定该后端，将以下代码加入你的配置中：
\nEMAIL_BACKEND = "django.core.mail.backends.dummy.EmailBackend"\n该后端不是为了在生产环境使用的——出于方便的目的，让你在开发阶段使用。
\n\n若你需要修改邮件发送的方式，你可以编写自定义的邮件后端。后面要在 EMAIL_BACKEND 配置项中指定你的后端类的路径。
Custom email backends should subclass BaseEmailBackend that is located in\nthe django.core.mail.backends.base module. A custom email backend must\nimplement the send_messages(email_messages) method. This method receives a\nlist of EmailMessage instances and returns the number of successfully\ndelivered messages. If your backend has any concept of a persistent session or\nconnection, you should also implement the open() and close() methods.\nRefer to smtp.EmailBackend for a reference implementation.
创建和关闭 SMTP 连接（或其它网络连接）是一项耗时的进程。如果你有很多封邮件要发送，复用连接就显得很有意义，而不是在每次发送邮件时创建和关闭连接。
\n有两种方式可以让邮件后端复用连接。
\n首先，你可以在连接上使用 send_messages() 方法。这需要一个 EmailMessage`（或其子类）实例的列表，并使用该单一连接发送它们。因此，在单个消息上设置的任何 :class:`connection 都会被忽略。
For example, if you have a function called get_notification_email() that\nreturns a list of EmailMessage objects representing some periodic\nemail you wish to send out, you could send these emails using a single call to\nsend_messages():
from django.core import mail\n\nconnection = mail.get_connection() # Use default email connection\nmessages = get_notification_email()\nconnection.send_messages(messages)\n在该例子中，调用 send_messages() 在后端创建了一条连接，发送完邮件列表后，关闭了这条连接。
第二种方式是在后端使用 open() 和 close() 手动控制连接。send_messages() 在连接已经建立的情况下不会控制连接的开关，故此，若你手动打开了连接，你可以决定何时关闭它。比如：
from django.core import mail\n\nconnection = mail.get_connection()\n\n# Manually open the connection\nconnection.open()\n\n# Construct an email message that uses the connection\nemail1 = mail.EmailMessage(\n "Hello",\n "Body goes here",\n "from@example.com",\n ["to1@example.com"],\n connection=connection,\n)\nemail1.send() # Send the email\n\n# Construct two more messages\nemail2 = mail.EmailMessage(\n "Hello",\n "Body goes here",\n "from@example.com",\n ["to2@example.com"],\n)\nemail3 = mail.EmailMessage(\n "Hello",\n "Body goes here",\n "from@example.com",\n ["to3@example.com"],\n)\n\n# Send the two emails in a single call -\nconnection.send_messages([email2, email3])\n# The connection was already open so send_messages() doesn't close it.\n# We need to manually close the connection.\nconnection.close()\n曾经有很多次，你并不想 Django 真的发送邮件。举个例子，在开发网站时，你可能并不期望发送成千上万封邮件——但你想要确保这些邮件将会在正确的时间，包含正确的内容，发送给正确的人。
\n在本地开发中配置电子邮件的最简单方法是使用 console 电子邮件后端。该后端将所有电子邮件重定向到 stdout，允许您查看邮件的内容。
文件 邮件后端在开发时也很有用——这个后端将每次 SMTP 连接的内容输出至一个文件，你可以在你闲暇时查看这个文件。
\n另一种方法是使用一个“哑”SMTP 服务器，它在本地接收电子邮件并将其显示到终端，但实际上并不发送任何内容。aiosmtpd 包提供了一种实现此目的的方法：
\npython -m pip install "aiosmtpd >= 1.4.5"\n\npython -m aiosmtpd -n -l localhost:8025\n这个命令将启动一个最小的 SMTP 服务器，监听在 localhost 的 8025 端口上。该服务器将打印所有电子邮件头和电子邮件正文到标准输出。然后，您只需要相应地设置 EMAIL_HOST 和 EMAIL_PORT。有关 SMTP 服务器选项的更详细讨论，请参阅 aiosmtpd 模块的文档。
关于发送邮件的单元测试资料，参见测试文档中 邮件服务 章节。
\n