Although Python makes sending e-mail relatively easy via the smtplib library, Django provides a couple of light wrappers over it. These wrappers are provided to make sending e-mail extra quick, to make it easy to test e-mail sending during development, and to provide support for platforms that can’t use SMTP.
The code lives in the django.core.mail module.
In two lines:
from django.core.mail import send_mail
send_mail('Subject here', 'Here is the message.', 'from@example.com',
['to@example.com'], fail_silently=False)
Mail is sent using the SMTP host and port specified in the EMAIL_HOST and EMAIL_PORT settings. The EMAIL_HOST_USER and EMAIL_HOST_PASSWORD settings, if set, are used to authenticate to the SMTP server, and the EMAIL_USE_TLS setting controls whether a secure connection is used.
Note
The character set of e-mail sent with django.core.mail will be set to the value of your DEFAULT_CHARSET setting.
The simplest way to send e-mail is using django.core.mail.send_mail().
The subject, message, from_email and recipient_list parameters are required.
django.core.mail.send_mass_mail() is intended to handle mass e-mailing.
datatuple is a tuple in which each element is in this format:
(subject, message, from_email, recipient_list)
fail_silently, auth_user and auth_password have the same functions as in send_mail().
Each separate element of datatuple results in a separate e-mail message. As in send_mail(), recipients in the same recipient_list will all see the other addresses in the e-mail messages' "To:" field.
For example, the following code would send two different messages to two different sets of recipients; however, only one connection to the mail server would be opened:
message1 = ('Subject here', 'Here is the message', 'from@example.com, ['first@example.com', 'other@example.com'])
message2 = ('Another Subject', 'Here is another message', 'from@example.com', ['second@test.com'])
send_mass_mail((message1, message2), fail_silently=False)
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.
django.core.mail.mail_admins() is a shortcut for sending an e-mail to the site admins, as defined in the ADMINS setting.
mail_admins() prefixes the subject with the value of the EMAIL_SUBJECT_PREFIX setting, which is "[Django] " by default.
The "From:" header of the e-mail will be the value of the SERVER_EMAIL setting.
This method exists for convenience and readability.
django.core.mail.mail_managers() is just like mail_admins(), except it sends an e-mail to the site managers, as defined in the MANAGERS setting.
This sends a single e-mail to john@example.com and jane@example.com, with them both appearing in the "To:":
send_mail('Subject', 'Message.', 'from@example.com',
['john@example.com', 'jane@example.com'])
This sends a message to john@example.com and jane@example.com, with them both receiving a separate e-mail:
datatuple = (
('Subject', 'Message.', 'from@example.com', ['john@example.com']),
('Subject', 'Message.', 'from@example.com', ['jane@example.com']),
)
send_mass_mail(datatuple)
Header injection is a security exploit in which an attacker inserts extra e-mail headers to control the "To:" and "From:" in e-mail messages that your scripts generate.
The Django e-mail functions outlined above all protect against header injection by forbidding newlines in header values. If any subject, from_email or recipient_list contains a newline (in either Unix, Windows or Mac style), the e-mail function (e.g. send_mail()) will raise django.core.mail.BadHeaderError (a subclass of ValueError) and, hence, will not send the e-mail. It's your responsibility to validate all data before passing it to the e-mail functions.
If a message contains headers at the start of the string, the headers will simply be printed as the first bit of the e-mail message.
Here's an example view that takes a subject, message and from_email from the request's POST data, sends that to admin@example.com and redirects to "/contact/thanks/" when it's done:
from django.core.mail import send_mail, BadHeaderError
def send_email(request):
subject = request.POST.get('subject', '')
message = request.POST.get('message', '')
from_email = request.POST.get('from_email', '')
if subject and message and from_email:
try:
send_mail(subject, message, from_email, ['admin@example.com'])
except BadHeaderError:
return HttpResponse('Invalid header found.')
return HttpResponseRedirect('/contact/thanks/')
else:
# In reality we'd use a form class
# to get proper validation errors.
return HttpResponse('Make sure all fields are entered and valid.')
Django's send_mail() and send_mass_mail() functions are actually thin wrappers that make use of the EmailMessage class.
Not all features of the EmailMessage class are available through the send_mail() and related wrapper functions. If you wish to use advanced features, such as BCC'ed recipients, file attachments, or multi-part e-mail, you'll need to create EmailMessage instances directly.
Note
This is a design feature. send_mail() and related functions were originally the only interface Django provided. However, the list of parameters they accepted was slowly growing over time. It made sense to move to a more object-oriented design for e-mail messages and retain the original functions only for backwards compatibility.
EmailMessage is responsible for creating the e-mail message itself. The e-mail backend is then responsible for sending the e-mail.
For convenience, EmailMessage provides a simple send() method for sending a single e-mail. If you need to send multiple messages, the e-mail backend API provides an alternative.
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.
For example:
email = EmailMessage('Hello', 'Body goes here', 'from@example.com',
['to1@example.com', 'to2@example.com'], ['bcc@example.com'],
headers = {'Reply-To': 'another@example.com'})
The class has the following methods:
send(fail_silently=False) sends the message. If a connection was specified when the e-mail 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.
message() constructs a django.core.mail.SafeMIMEText object (a subclass of Python's email.MIMEText.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 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 an email.MIMEBase.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 e-mail, 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.
For example:
message.attach('design.png', img_data, 'image/png')
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. The simplest use would be:
message.attach_file('/images/weather_map.png')
It can be useful to include multiple versions of the content in an e-mail; the classic example is to send both text and HTML versions of a message. With Django's e-mail library, you can do this using the EmailMultiAlternatives class. This subclass of EmailMessage has an attach_alternative() method for including extra versions of the message body in the e-mail. All the other methods (including the class initialization) are inherited directly from EmailMessage.
To send a text and HTML combination, you could write:
from django.core.mail import EmailMultiAlternatives
subject, from_email, to = 'hello', 'from@example.com', 'to@example.com'
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()
By default, the MIME type of the body parameter in an EmailMessage is "text/plain". It is good practice to leave this alone, because it guarantees that any recipient will be able to read the e-mail, regardless of their mail client. However, if you are confident that your recipients can handle an alternative content type, you can use the content_subtype attribute on the EmailMessage class to change the main content type. The major type will always be "text", but you can change the subtype. For example:
msg = EmailMessage(subject, html_content, from_email, [to])
msg.content_subtype = "html" # Main content is now text/html
msg.send()
The actual sending of an e-mail is handled by the e-mail backend.
The e-mail backend class has the following methods:
The get_connection() function in django.core.mail returns an instance of the e-mail backend that you can use.
By default, a call to get_connection() will return an instance of the e-mail 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 e-mail sending process will be silently ignored.
All other arguments are passed directly to the constructor of the e-mail backend.
Django ships with several e-mail 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 e-mail sending requirements, you can write your own e-mail backend.
This is the default backend. E-mail will be sent through a SMTP server. The server address and authentication credentials are set in the EMAIL_HOST, EMAIL_PORT, EMAIL_HOST_USER, EMAIL_HOST_PASSWORD and EMAIL_USE_TLS settings in your settings file.
The SMTP backend is the default configuration inherited by Django. If you want to specify it explicitly, put the following in your settings:
EMAIL_BACKEND = 'django.core.mail.backends.smtp.EmailBackend'
SMTPConnection objects
Prior to version 1.2, Django provided a SMTPConnection class. This class provided a way to directly control the use of SMTP to send e-mail. This class has been deprecated in favor of the generic e-mail backend API.
For backwards compatibility SMTPConnection is still available in django.core.mail as an alias for the SMTP backend. New code should use get_connection() instead.
Instead of sending out real e-mails the console backend just writes the e-mails that would be send to the standard output. By default, the console backend writes to stdout. You can use a different stream-like object by providing the stream keyword argument when constructing the connection.
To specify this backend, put the following in your settings:
EMAIL_BACKEND = 'django.core.mail.backends.console.EmailBackend'
This backend is not intended for use in production -- it is provided as a convenience that can be used during development.
The file backend writes e-mails to a file. A new file is created for each new session that is opened on this backend. The directory to which the files are written is either taken from the EMAIL_FILE_PATH setting or from the file_path keyword when creating a connection with get_connection().
To specify this backend, put the following in your settings:
EMAIL_BACKEND = 'django.core.mail.backends.filebased.EmailBackend'
EMAIL_FILE_PATH = '/tmp/app-messages' # change this to a proper location
This backend is not intended for use in production -- it is provided as a convenience that can be used during development.
The 'locmem' backend stores messages in a special attribute of the django.core.mail module. The outbox attribute is created when the first message is sent. It's a list with an EmailMessage instance for each message that would be send.
To specify this backend, put the following in your settings:
EMAIL_BACKEND = 'django.core.mail.backends.locmem.EmailBackend'
This backend is not intended for use in production -- it is provided as a convenience that can be used during development and testing.
As the name suggests the dummy backend does nothing with your messages. To specify this backend, put the following in your settings:
EMAIL_BACKEND = 'django.core.mail.backends.dummy.EmailBackend'
This backend is not intended for use in production -- it is provided as a convenience that can be used during development.
If you need to change how e-mails are sent you can write your own e-mail backend. The EMAIL_BACKEND setting in your settings file is then the Python import path for your backend class.
Custom e-mail backends should subclass BaseEmailBackend that is located in the django.core.mail.backends.base module. A custom e-mail 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.
Establishing and closing an SMTP connection (or any other network connection, for that matter) is an expensive process. If you have a lot of e-mails to send, it makes sense to reuse an SMTP connection, rather than creating and destroying a connection every time you want to send an e-mail.
There are two ways you tell an e-mail 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 e-mail you wish to send out, you could send these e-mails using a single call to send_messages:
from django.core import mail
connection = mail.get_connection() # Use default e-mail 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 e-mail 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 e-mail message that uses the connection
email1 = mail.EmailMessage('Hello', 'Body goes here', 'from@example.com',
['to1@example.com'], connection=connection)
email1.send() # Send the e-mail
# Construct two more messages
email2 = mail.EmailMessage('Hello', 'Body goes here', 'from@example.com',
['to2@example.com'])
email3 = mail.EmailMessage('Hello', 'Body goes here', 'from@example.com',
['to3@example.com'])
# Send the two e-mails 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()
There are times when you do not want Django to send e-mails at all. For example, while developing a Web site, you probably don't want to send out thousands of e-mails -- but you may want to validate that e-mails will be sent to the right people under the right conditions, and that those e-mails will contain the correct content.
The easiest way to test your project's use of e-mail is to use the console e-mail backend. This backend redirects all e-mail to stdout, allowing you to inspect the content of mail.
The file e-mail backend can also be useful during development -- this backend dumps the contents of every SMTP connection to a file that can be inspected at your leisure.
Another approach is to use a "dumb" SMTP server that receives the e-mails locally and displays them to the terminal, but does not actually send anything. Python has a built-in way to accomplish this with a single command:
python -m smtpd -n -c DebuggingServer localhost:1025
This command will start a simple SMTP server listening on port 1025 of localhost. This server simply prints to standard output all e-mail headers and the e-mail body. You then only need to set the EMAIL_HOST and EMAIL_PORT accordingly, and you are set.
For a more detailed discussion of testing and processing of e-mails locally, see the Python documentation on the SMTP Server.
The SMTPConnection class has been deprecated in favor of the generic e-mail backend API.
For backwards compatibility SMTPConnection is still available in django.core.mail as an alias for the SMTP backend. New code should use get_connection() instead.
Dec 26, 2011