Although Python makes sending e-mail relatively easy via the smtplib library, Django provides a couple of light wrappers over it, to make sending e-mail extra quick.
The code lives in a single module: django.core.mail.
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 the function django.core.mail.send_mail(). Here's its definition:
- send_mail(subject, message, from_email, recipient_list, fail_silently=False, auth_user=None, auth_password=None)¶
The subject, message, from_email and recipient_list parameters are required.
django.core.mail.send_mass_mail() is intended to handle mass e-mailing. Here's the definition:
- send_mass_mail(datatuple, fail_silently=False, auth_user=None, auth_password=None)¶
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.
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. Here's the definition:
- mail_admins(subject, message, fail_silently=False)¶
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. Here's the definition:
- mail_managers(subject, message, fail_silently=False)¶
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 and SMTPConnection classes in django.core.mail. If you ever need to customize the way Django sends e-mail, you can subclass these two classes to suit your needs.
Note
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.
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.
In general, EmailMessage is responsible for creating the e-mail message itself. SMTPConnection is responsible for the network connection side of the operation. This means you can reuse the same connection (an SMTPConnection instance) for multiple messages.
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, using either the connection that is specified in the connection attribute, or creating a new connection if none already exists. 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 it to 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 SMTPConnection class is initialized with the host, port, username and password for the SMTP server. If you don't specify one or more of those options, they are read from your settings file.
If you're sending lots of messages at once, the send_messages() method of the SMTPConnection class is useful. It takes a list of EmailMessage instances (or subclasses) and sends them over 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 this with:
connection = SMTPConnection() # Use default settings for connection
messages = get_notification_email()
connection.send_messages(messages)
The are times when you do not want Django to send e-mails at all. For example, while developing a website, 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 a "dumb" e-mail 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 email headers and the email body. You then only need to set the EMAIL_HOST and EMAIL_PORT accordingly, and you are set.
For more entailed testing and processing of e-mails locally, see the Python documentation on the SMTP Server.
Sep 20, 2009