Sending e-mail¶
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
.
Quick example¶
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.
send_mail()¶
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.
subject
: A string.message
: A string.from_email
: A string.recipient_list
: A list of strings, each an e-mail address. Each member ofrecipient_list
will see the other recipients in the “To:” field of the e-mail message.fail_silently
: A boolean. If it’sFalse
,send_mail
will raise ansmtplib.SMTPException
. See the smtplib docs for a list of possible exceptions, all of which are subclasses ofSMTPException
.auth_user
: The optional username to use to authenticate to the SMTP server. If this isn’t provided, Django will use the value of theEMAIL_HOST_USER
setting.auth_password
: The optional password to use to authenticate to the SMTP server. If this isn’t provided, Django will use the value of theEMAIL_HOST_PASSWORD
setting.
send_mass_mail()¶
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.
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.
mail_admins()¶
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.
mail_managers() function¶
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)¶
Examples¶
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)
Preventing header injection¶
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.')
The EmailMessage and SMTPConnection classes¶
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.
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 e-mail.body
: The body text. This should be a plain text message.from_email
: The sender’s address. Bothfred@example.com
andFred <fred@example.com>
forms are legal. If omitted, theDEFAULT_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 e-mail.connection
: AnSMTPConnection
instance. Use this parameter if you want to use the same connection for multiple messages. If omitted, a new connection is created whensend()
is called.attachments
: A list of attachments to put on the message. These can be eitheremail.MIMEBase.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 e-mail message.
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 theconnection
attribute, or creating a new connection if none already exists. If the keyword argumentfail_silently
isTrue
, exceptions raised while sending the message will be quashed.message()
constructs adjango.core.mail.SafeMIMEText
object (a subclass of Python’semail.MIMEText.MIMEText
class) or adjango.core.mail.SafeMIMEMultipart
object holding the message to be sent. If you ever need to extend theEmailMessage
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 theto
orbcc
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 callattach()
: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
andmimetype
.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 andmimetype
is the optional MIME type for the attachment. If you omitmimetype
, 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')
Sending alternative content types¶
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()
SMTPConnection Objects¶
-
class
SMTPConnection
¶
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)
Testing e-mail sending¶
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.