send_mass_mail() vs. send_mail()¶

The main difference between send_mass_mail() and send_mail() is that send_mail() opens a connection to the mail server each time it’s executed, while send_mass_mail() uses a single connection for all of its messages. This makes send_mass_mail() slightly more efficient.

EmailMessage Objects¶

class EmailMessage¶

The EmailMessage class is initialized with the following parameters (in the given order, if positional arguments are used). All parameters are optional and can be set at any time prior to calling the send() method.

• subject: The subject line of the email.
• body: The body text. This should be a plain text message.
• from_email: The sender’s address. Both fred@example.com and "Fred" <fred@example.com> forms are legal. If omitted, the DEFAULT_FROM_EMAIL setting is used.
• to: A list or tuple of recipient addresses.
• bcc: A list or tuple of addresses used in the “Bcc” header when sending the email.
• connection: An email backend instance. Use this parameter if you want to use the same connection for multiple messages. If omitted, a new connection is created when send() is called.
• attachments: A list of attachments to put on the message. These can be either MIMEBase instances, or (filename, content, mimetype) triples.
• headers: A dictionary of extra headers to put on the message. The keys are the header name, values are the header values. It’s up to the caller to ensure header names and values are in the correct format for an email message. The corresponding attribute is extra_headers.
• cc: A list or tuple of recipient addresses used in the “Cc” header when sending the email.
• reply_to: A list or tuple of recipient addresses used in the “Reply-To” header when sending the email.

예시:

from django.core.mail import EmailMessage

email = EmailMessage(
    "Hello",
    "Body goes here",
    "[email protected]",
    ["[email protected]", "[email protected]"],
    ["[email protected]"],
    reply_to=["[email protected]"],
    headers={"Message-ID": "foo"},
)

The class has the following methods:

• send(fail_silently=False) sends the message. If a connection was specified when the email was constructed, that connection will be used. Otherwise, an instance of the default backend will be instantiated and used. If the keyword argument fail_silently is True, exceptions raised while sending the message will be quashed. An empty list of recipients will not raise an exception. It will return 1 if the message was sent successfully, otherwise 0.

• message() constructs a django.core.mail.SafeMIMEText object (a subclass of Python’s MIMEText class) or a django.core.mail.SafeMIMEMultipart object holding the message to be sent. If you ever need to extend the EmailMessage class, you’ll probably want to override this method to put the content you want into the MIME object.

• recipients() returns a list of all the recipients of the message, whether they’re recorded in the to, cc or bcc attributes. This is another method you might need to override when subclassing, because the SMTP server needs to be told the full list of recipients when the message is sent. If you add another way to specify recipients in your class, they need to be returned from this method as well.

• attach() creates a new file attachment and adds it to the message. There are two ways to call attach():

  • You can pass it a single argument that is a MIMEBase instance. This will be inserted directly into the resulting message.

  • Alternatively, you can pass attach() three arguments: filename, content and mimetype. filename is the name of the file attachment as it will appear in the email, content is the data that will be contained inside the attachment and mimetype is the optional MIME type for the attachment. If you omit mimetype, the MIME content type will be guessed from the filename of the attachment.

    예시:

    message.attach("design.png", img_data, "image/png")
    

    If you specify a mimetype of message/rfc822, it will also accept django.core.mail.EmailMessage and email.message.Message.

    For a mimetype starting with text/, content is expected to be a string. Binary data will be decoded using UTF-8, and if that fails, the MIME type will be changed to application/octet-stream and the data will be attached unchanged.

    In addition, message/rfc822 attachments will no longer be base64-encoded in violation of RFC 2046#section-5.2.1, which can cause issues with displaying the attachments in Evolution and Thunderbird.

• attach_file() creates a new attachment using a file from your filesystem. Call it with the path of the file to attach and, optionally, the MIME type to use for the attachment. If the MIME type is omitted, it will be guessed from the filename. You can use it like this:

  message.attach_file("/images/weather_map.png")
  

  For MIME types starting with text/, binary data is handled as in attach().

from django.core.mail import EmailMultiAlternatives

subject, from_email, to = "hello", "[email protected]", "[email protected]"
text_content = "This is an important message."
html_content = "<p>This is an <strong>important</strong> message.</p>"
msg = EmailMultiAlternatives(subject, text_content, from_email, [to])
msg.attach_alternative(html_content, "text/html")
msg.send()

msg = EmailMessage(subject, html_content, from_email, [to])
msg.content_subtype = "html"  # Main content is now text/html
msg.send()

이메일 백엔드 인스턴스 얻기¶

The get_connection() function in django.core.mail returns an instance of the email backend that you can use.

get_connection(backend=None, fail_silently=False, *args, **kwargs)¶

By default, a call to get_connection() will return an instance of the email backend specified in EMAIL_BACKEND. If you specify the backend argument, an instance of that backend will be instantiated.

The fail_silently argument controls how the backend should handle errors. If fail_silently is True, exceptions during the email sending process will be silently ignored.

All other arguments are passed directly to the constructor of the email backend.

Django ships with several email sending backends. With the exception of the SMTP backend (which is the default), these backends are only useful during testing and development. If you have special email sending requirements, you can write your own email backend.

EMAIL_BACKEND = "django.core.mail.backends.console.EmailBackend"

EMAIL_BACKEND = "django.core.mail.backends.filebased.EmailBackend"
EMAIL_FILE_PATH = "/tmp/app-messages"  # change this to a proper location

EMAIL_BACKEND = "django.core.mail.backends.locmem.EmailBackend"

EMAIL_BACKEND = "django.core.mail.backends.dummy.EmailBackend"

맞춤 이메일 백엔드 정의하기¶

If you need to change how emails are sent you can write your own email backend. The EMAIL_BACKEND setting in your settings file is then the Python import path for your backend class.

Custom email backends should subclass BaseEmailBackend that is located in the django.core.mail.backends.base module. A custom email backend must implement the send_messages(email_messages) method. This method receives a list of EmailMessage instances and returns the number of successfully delivered messages. If your backend has any concept of a persistent session or connection, you should also implement the open() and close() methods. Refer to smtp.EmailBackend for a reference implementation.

여러 통의 이메일 보내기¶

Establishing and closing an SMTP connection (or any other network connection, for that matter) is an expensive process. If you have a lot of emails to send, it makes sense to reuse an SMTP connection, rather than creating and destroying a connection every time you want to send an email.

There are two ways you tell an email backend to reuse a connection.

Firstly, you can use the send_messages() method. send_messages() takes a list of EmailMessage instances (or subclasses), and sends them all using a single connection.

For example, if you have a function called get_notification_email() that returns a list of EmailMessage objects representing some periodic email you wish to send out, you could send these emails using a single call to send_messages:

from django.core import mail

connection = mail.get_connection()  # Use default email connection
messages = get_notification_email()
connection.send_messages(messages)

In this example, the call to send_messages() opens a connection on the backend, sends the list of messages, and then closes the connection again.

The second approach is to use the open() and close() methods on the email backend to manually control the connection. send_messages() will not manually open or close the connection if it is already open, so if you manually open the connection, you can control when it is closed. For example:

from django.core import mail

connection = mail.get_connection()

# Manually open the connection
connection.open()

# Construct an email message that uses the connection
email1 = mail.EmailMessage(
    "Hello",
    "Body goes here",
    "[email protected]",
    ["[email protected]"],
    connection=connection,
)
email1.send()  # Send the email

# Construct two more messages
email2 = mail.EmailMessage(
    "Hello",
    "Body goes here",
    "[email protected]",
    ["[email protected]"],
)
email3 = mail.EmailMessage(
    "Hello",
    "Body goes here",
    "[email protected]",
    ["[email protected]"],
)

# Send the two emails in a single call -
connection.send_messages([email2, email3])
# The connection was already open so send_messages() doesn't close it.
# We need to manually close the connection.
connection.close()