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Django Email Attachment Fix

DodaTech Updated 2026-06-24 2 min read

In this tutorial, you'll learn about Django Email Attachment Fix. We cover key concepts, practical examples, and best practices.

The Problem

You need to send invoices, reports, or images as email attachments. Django's send_mail doesn't support attachments.

Quick Fix

Wrong — send_mail without attachments

from django.core.mail import send_mail

send_mail(
    'Your Invoice',
    'Invoice attached.',
    'billing@dodatech.com',
    [user.email],
)

Output: Email sent but no attachment. The message says "Invoice attached" but nothing is there.

Correct — EmailMessage with attachment

from django.core.mail import EmailMessage
from django.conf import settings
import os

def send_invoice(user, invoice_pdf_path):
    email = EmailMessage(
        'Your Invoice from DodaTech',
        'Please find your invoice attached.',
        'billing@dodatech.com',
        [user.email],
    )

    with open(invoice_pdf_path, 'rb') as f:
        email.attach(
            os.path.basename(invoice_pdf_path),  # Filename
            f.read(),                              # Content
            'application/pdf',                     # MIME type
        )

    email.send()

Attaching file from upload

def send_document(user, uploaded_file):
    email = EmailMessage(
        'Document Shared',
        f'{user.username} shared a document with you.',
        'noreply@dodatech.com',
        [user.email],
    )
    email.attach(
        uploaded_file.name,
        uploaded_file.read(),
        uploaded_file.content_type,
    )
    email.send()

Multiple attachments

def send_report(email_address, csv_path, charts_dir):
    email = EmailMessage('Monthly Report', 'Your report is ready.',
                         'reports@dodatech.com', [email_address])

    # CSV attachment
    with open(csv_path, 'rb') as f:
        email.attach('report.csv', f.read(), 'text/csv')

    # Multiple chart images
    for chart_file in Path(charts_dir).glob('*.png'):
        with open(chart_file, 'rb') as f:
            email.attach(chart_file.name, f.read(), 'image/png')

    email.send()

Inline image in HTML email

def send_html_with_image(user):
    email = EmailMultiAlternatives(
        'Product Update',
        'Your product update',
        'noreply@dodatech.com',
        [user.email],
    )

    # Attach inline image
    with open('static/img/logo.png', 'rb') as f:
        email.attach('logo.png', f.read(), 'image/png')

    # Reference in HTML
    html = '<img src="cid:logo.png" alt="Logo"><p>New features available!</p>'
    email.attach_alternative(html, 'text/html')
    # Map CID
    email.content_subtype = 'html'
    email.mixed_subtype = 'related'

    email.send()

Attachment from in-memory file

import io
import csv
from django.core.mail import EmailMessage

def send_csv_report(users):
    output = io.StringIO()
    writer = csv.writer(output)
    writer.writerow(['Username', 'Email', 'Joined'])
    for u in users:
        writer.writerow([u.username, u.email, u.date_joined])

    email = EmailMessage(
        'User Report', 'CSV report attached.',
        'reports@dodatech.com', ['admin"@dodatech".com'],
    )
    email.attach('users.csv', output.getvalue(), 'text/csv')
    email.send()

Prevention

  • Use EmailMessage or EmailMultiAlternatives instead of send_mail when you need attachments.
  • Always specify the MIME type for attachments.
  • For large attachments, consider hosting the file and including a link instead.

Common Mistakes with email attachment

  1. Mixing let bindings with <- bindings in do notation, producing type errors
  2. Overlapping type class instances that cause GHC to reject the program with ambiguous dispatch errors
  3. Non-exhaustive pattern matches that compile with warnings then crash at runtime

These mistakes appear frequently in real-world DJANGO code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

FAQ

### What MIME type should I use for PDFs?

application/pdf. For images: image/jpeg, image/png. For CSV: text/csv. For ZIP: application/zip.

Is there a size limit for email attachments?

Most email providers limit attachments to 25MB. For larger files, upload to S3 and send a download link.

Can I attach a file without saving it to disk?

Yes. Use email.attach(filename, content, mimetype) where content is bytes or a string. The file exists only in memory.

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