Python Email Attachments Made Easy: A Step-by-Step Guide to Sending Files via Email

Prerequisites

Before we get started, you'll need to have the following prerequisites in place:

• A working Python environment, such as Anaconda or Python.org
• A valid email address and password for an email service provider, such as Gmail or Yahoo
• Basic knowledge of Python programming concepts
• Basic understanding of how to send emails with Python

Step 1: Import the required Libraries

To send email attachments we need two built-in python libraries : email and smtplib.

• email library is used to create and format email messages and attachments to them
• smtplib library is used to send email messages via SMTP(Simple Mail Transfer Protocol). SMTP is the protocol used to send emails, regardless of the language you are using.

Let's start by opening a new Python file main.py and writing the following code:

import smtplib
from email.message import EmailMessage

Step 2: Set Up Your Email Credentials

Next, we'll specify our email credentials, such as your email address, password, and the SMTP server settings for your email service provider (e.g. Gmail, Yahoo, Outlook etc). Here's an example of how to set up a Gmail account:

# Set up email account information
email_address = "your_email@gmail.com"
email_password = "your_password"
smtp_server = "smtp.gmail.com"
smtp_port = 587

These credentials will be latest passed on to the specified SMTP server and port. Note, if you're using a different email provider, you'll need to use the appropriate SMTP server settings. Here are the SMTP settings for some popular email providers :

• Outlook
• Yahoo
• AWS SES

Step 3: Create Your Email Message

To create an email message with attachments, we'll need to import the EmailMessage class we imported earlier from email.message library. Let's create a simple email with a a short subject, body, and one attachment:

# Create email message
msg = EmailMessage()
msg['Subject'] = 'Re: Hello, World!'
msg['From'] = email_address
msg['To'] = 'recipient_email@example.com'
msg.set_content('Hello Gilfoyle, this is a test email with an attachment. -Dinesh')
with open('attachment.txt', 'rb') as f:
    file_data = f.read()
msg.add_attachment(file_data, maintype='text', subtype='plain', filename='attachment.txt')

In this example, we created an email message with the subject 'Re: Hello, World!', with body "Hello, this is a test email with an attachment.". We have also added one attachment named "attachment.txt" using the add_attachment method, this method reads the file data and sets the attachment's content type to "text/plain."

Step 4: Send Your Email Message

Once we are done with the above steps, let's now send out email with attachment using smtplib library.

# Send email message
with smtplib.SMTP(smtp_server, smtp_port) as server:
    server.starttls()
    server.login(email_address, email_password)
    server.send_message(msg)

Here we first created a SMTP server object using smtplib.SMTP class. This object then makes a secure connection to the SMTP server, logs in with the credentials we specified earlier. We then send the email message using send_message().

Additional Tips and Tricks

Let's discuss some widely used cases that will be helpful while working with email attachments :

Adding Multiple Attachments

To add multiple attachments to your email message, simply call add_attachment() multiple times with different filenames and file data.

with open('file1.txt', 'rb') as f1, open('file2.txt', 'rb') as f2:
    file1_data = f1.read()
    file2_data = f2.read()
msg.add_attachment(file1_data, maintype='text', subtype='plain', filename='file1.txt')
msg.add_attachment(file2_data, maintype='text', subtype='plain', filename='file2.txt')

Specifying Attachment Content Types

The maintype and subtype arguments for add_attachment() determine the content type of the attachment. Here are some common content types:

• Text: maintype='text', subtype='plain'
• HTML: maintype='text', subtype='html'
• Images: maintype='image', subtype='jpeg' or maintype='image', subtype='png'
• PDFs: maintype='application', subtype='pdf'

Handling Large Attachments

If you're working with large attachments, you may run into memory issues when reading the file data into memory with read(). To avoid this, you can use the EmailMessage.iter_attachments() method to iterate over the attachment data in chunks.

with open('large_file.txt', 'rb') as f:
    while True:
        file_data = f.read(1024)
        if not file_data:
            break
        msg.add_attachment(file_data, maintype='text', subtype='plain', filename='large_file.txt')

Using HTML in Your Email Message

Most of the times we want to send fancy HTML templates as emails instead of boring-looking plaintext emails. To achieve this, simply set the message content to an HTML string using msg.set_content().

msg.set_content('<html><body><h1>Test Email with HTML</h1><p>This is a test email with HTML content.</p></body></html>', subtype='html')

Frequently Asked Questions

How do I handle errors when sending email attachments with Python?
Using Python's exception handling you can catch and handle these errors. Based on the severity, you can log and retry on your exceptions as well.

Depending on the error you can use exception handling to catch and handle these errors. You can add logging, retries as well to help diagnose and retry for failures.

What file types can I send as email attachments with Python?
You can send any file type including binaries as email attachments with Python. Remember, some mail servers may block the attachments if the file size, type is a potential security concern.

Can I use Python to receive email attachments?
Yes, to receive email with attachments in Python you can use imaplib library. You can then list or get emails, download attachments etc.

How can I ensure the security of email attachments sent with Python?
Security for email and its attachments are dependent on the email service provider. Make sure you use a secure email service provider, keep strong passwords etc.

How do I test my email attachments to make sure they work?
You can test by sending test emails with attachments to yourself or other mock email services like mailosaur or mailtrap. You can also test email attachments with varying attachment size etc.

Conclusion

That's all! In this blog post we saw how we can send email attachments with python easily using the email and smtplib libraries. Feel free to reach out or comment below for your doubts. Happy emailing!