Add multipart message capability to django.core.mail

mail.py patch

Sorry, forgot to hit the "code block" button. Here's try two for that example code.

msg = mail.SafeMIMEMultipart('alternative', charset="utf-8") 
msg.attach(mail.SafeMIMEText("example text part", "text"))
msg.attach(mail.SafeMIMEText("<p>example <b>html</b> part", "html")) 
mail.send_mail("example multipart mail", msg, "me@example.com", ["you@example.com",])

Maybe someone can integrate this patch into magic-removal branch?

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This is great, and I want to check it in. However, it needs docs added to mail.txt first.

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Does anybody knows when this patch will be integrated into trunk?

I am attaching a patch that adds multipart message capability. This is slightly different from multipart_mail.diff, in that Django creates the individual mime parts and attaches them.

Example

    attachments = [
        ('image.png', open('/home/user/image.png', 'rb')),
        ('audio.mp3', open('/home/user/audio.mp3', 'rb')),
    ]
    send_mail(subject, body, sender, recipients, attachments=attachments)

Forgot to add that send_mass_mail() might not work as expected, when attachments is reused for multiple datatuples.

Similar to mail_attachment.diff, but accepts str objects instread of file objects

#3307 has a competing version of this feature, along with some other details.

Replying to ubernostrum from #3307:

Hmm. I thought I'd searched on this previously and not found anything, but I guess I was wrong. #1541 has a safer implementation of the multipart stuff.

Can someone please test the patch. Also with adding all these new features to an email here and in #3307, it seems like the datatuple is becoming smelly. Perhaps some sort of EmailMessage class storing all these different data pieced as attributes?

Replying to Gary Wilson <gary.wilson@gmail.com>:

Perhaps some sort of EmailMessage class storing all these different data pieced as attributes?

Created #3366.

I would like the third patch to be applied and this bug closed. We can start working on #3366, but that should not keep this bug waiting.

Also, maybe the Python bug mentioned in #3104 should be added as a note in the documentation of this new feature.

Actually, I guess #3104 is only for multipart form uploads, sorry.

Jacob mentioned that the only thing holding this back was docs, and docs are now here.

This ticket contains three competing implementations of the same feature, with another option on #3307. The version that was initially accepted by Jacob still isn't documented. There needs to be some public discussion on which option to adopt, and how that choice integrates with #3366.

Replying to russellm:

This ticket contains three competing implementations of the same feature, with another option on #3307. The version that was initially accepted by Jacob still isn't documented. There needs to be some public discussion on which option to adopt, and how that choice integrates with #3366.

Mails to the developers mailing list have not induced a discussion. What should be the plan of action if there is no or insufficient response?

I am the original author of this patch, which has now grown into a tangle. I'd be willing to consolidate the various patches, as I don't think they are really conflicting all that much.

The combined version would:

1) Use the idea from #3366, making an EmailMessage? class, which is really just an extension of the "SafeMimeMultipart?" I made in the original patch.

2) Add the bcc_list idea from #3307

3) Add the convenience method for adding a list of attachments at once.

How does that sound?

@bruce

Sounds like a good approach to me. Show me the code! :-)

Replying to bruce@coderseye.com:

How does that sound?

Sounds good. I have a few concerns/comments. I prefer an approach where I do not have to know what SafeMIMEMultipart is. It is not clear how the EmailMessage? class will maintain backward compatibility. We will be spending a lot of time accepting an interface and implementation for EmailMessage?, and have to disturb everyone when that patch is applied. Not many people are interested, this is not newforms ;) I'd recommend applying patch 3 now and after that, working on #3366.

Replying to anonymous:

It is not clear how the EmailMessage? class will maintain backward compatibility.

Well, it's not completely necessary to maintain backward compatibility, as it's not guaranteed until 1.0.

We will be spending a lot of time accepting an interface and implementation for EmailMessage, and have to disturb everyone when that patch is applied. Not many people are interested, this is not newforms ;) I'd recommend applying patch 3 now and after that, working on #3366.

The patch for this ticket maintains backwards compatibility since it allows for a variable length datatuple, but what happens when it's time to add the features from other tickets? The interface would probably have to be changed anyway. If the interface is fixed first (with EmailMessage in #3366?), then all these features from the various tickets could be added afterwards (separately or together) without breaking anything.

Well folks here is a quick mash of Bruce's #1541 and Gary Wilson's #3366 patch, against rev 5468. Plus a convenience parameter for sending HTML.

I think all we need now, is to make it handle images and other mime types transparently too. I haven't played with that stuff in python before and have no immediate need right now - anyone else keen?

unified #1541 and #3366 - needs improvement to handle other mimetypes

Using the new EmailMessage? system, we can already implement attachments without much duplication and without patching the source. I've had to do it just now, and below is the code I came up with (based on the code in the patch). Only EmailWithAttachments?.message() has any significant duplication of core code.

I'm not sure what further work on changing the EmailMessage? class and send_mail function is planned. In case nothing further is done, or in case it takes a while, the code below may help other people. (NB, I haven't tested it massively, it works for my usage).

from django.core.mail import EmailMessage, SMTPConnection, SafeMIMEText, Header, BadHeaderError, formatdate, make_msgid
from email import Encoders
from email.MIMEBase import MIMEBase
from email.MIMEMultipart import MIMEMultipart
from django.conf import settings

"""
Utilities for sending email with attachments
"""

class SafeMIMEMultipart(MIMEMultipart): 
    def __setitem__(self, name, val): 
        "Forbids multi-line headers, to prevent header injection." 
        if '\n' in val or '\r' in val: 
            raise BadHeaderError, "Header values can't contain newlines (got %r for header %r)" % (val, name) 
        if name == "Subject": 
            val = Header(val, settings.DEFAULT_CHARSET) 
        MIMEMultipart.__setitem__(self, name, val) 
 
    def attachFile(self, filename, content, mimetype): 
        maintype, subtype = mimetype.split('/', 1) 
        msg = MIMEBase(maintype, subtype) 
        msg.set_payload(content) 
        Encoders.encode_base64(msg) 
        msg.add_header('Content-Disposition', 'attachment', filename=filename) 
        MIMEMultipart.attach(self, msg) 

class EmailWithAttachments(EmailMessage):
    def __init__(self, *args, **kwargs):
        attachments = kwargs.pop('attachments', None)
        super(EmailWithAttachments, self).__init__(*args, **kwargs)
        self.attachments = attachments

    def message(self):
        simple_msg = SafeMIMEText(self.body, 'plain', settings.DEFAULT_CHARSET)
        if self.attachments:
            # This is a multipart mail
            msg = SafeMIMEMultipart()
            # First the body
            msg.attach(simple_msg)
            # Then the various files to be attached.
            for (filename, content, mimetype) in self.attachments:
                msg.attachFile(filename, content, mimetype)
        else:
            msg = simple_msg
        
        msg['Subject'] = self.subject
        msg['From'] = self.from_email
        msg['To'] = ', '.join(self.to)
        msg['Date'] = formatdate()
        msg['Message-ID'] = make_msgid()
        if self.bcc:
            msg['Bcc'] = ', '.join(self.bcc)
        return msg

def send_mail_with_attachments(subject, message, from_email, recipient_list, 
                              fail_silently=False, auth_user=None, auth_password=None, attachments=None): 
    connection = SMTPConnection(username=auth_user, password=auth_password,
                                 fail_silently=fail_silently)
    return EmailWithAttachments(subject, message, from_email, recipient_list,
                                 connection=connection, attachments=attachments).send()

Looks good, just need to get this stuff into core. Multipart, file attachments, transparent HTML, and possibly even a convenience function for template/context merging.

Patch to add attachments to django.core.mail

I have a similar patch, which I improved a bit using lukeplant's example, which allows you to add attachments to a EmailMessage? object. I also added a render_to_mail shortcut:

def render_to_mail(*args, **kwargs):
    return EmailMessage(body=loader.render_to_string(*args, **kwargs))

So my typical usage is:

m = render_to_mail('emails/foo.html', {'var': 'bar'})
m.attach_file('files/some_file.pdf')
m.subject = 'Here is your file'
m.to = ['nick.lane.au@gmail.com']
m.send()

Slight change to patch, added docs

Slight change to patch, added docs (last patch broken)

Slight change to patch, added docs (last patch broken)

Sorry about the bad patches... I swore the last one would work. I'll have to wait a week till I'm back at home and can do a proper patch against SVN. I can also add in the tests I have and make sure they work against SVN too.

Feel free to remove mail.2.diff -> mail.4.diff.

No need to worry about updating the patches any further, Nick. I'm partway through merging them into trunk. Using most of your design, with only a few small tweaks. Should have something committed in the next day or two.

(In [5547]) Fixed #1541 -- Added ability to create multipart email messages. Thanks, Nick Lane.