Python Email Automation: Send Personalized Emails at Scale

You need to send 200 personalized emails. Each one needs the recipient's name, company, and a customized offer based on their industry. You could spend 6 hours manually writing and sending them. Or you could spend 20 minutes writing a Python script and let it handle everything while you grab coffee.

Email automation with Python isn't just about bulk sending. It's about personalizing at scale—making each recipient feel like you wrote specifically to them, even when you're sending to thousands.

Let me show you how to build a production-ready email automation system with Python.

What You'll Learn

By the end of this tutorial, you'll be able to:

Send personalized emails to hundreds of recipients
Pull recipient data from CSV, Excel, or databases
Customize email content based on recipient attributes
Handle attachments (PDFs, images, documents)
Track email delivery and handle failures
Avoid spam filters and maintain deliverability
Schedule automated email campaigns

All with Python and free/low-cost tools.

Prerequisites

What you need:

Python 3.8+ installed
Basic Python knowledge (loops, functions, string formatting)
An email account (Gmail, Outlook, or SMTP service)
20-30 minutes

Libraries we'll use:

smtplib (built-in, sends emails via SMTP)
email (built-in, constructs email messages)
pandas (data handling)
jinja2 (email templating)
python-dotenv (secure credential storage)

Step 1: Setup and Simple Email

First, let's send a single email to understand the basics.

Install dependencies:

bash

1pip install pandas jinja2 python-dotenv openpyxl

Create your first email script:

python

1import smtplib
2from email.mime.text import MIMEText
3from email.mime.multipart import MIMEMultipart
4
5def send_simple_email(sender_email, sender_password, recipient_email, subject, body):
6    """Send a plain text email"""
7    
8    # Create message
9    message = MIMEMultipart()
10    message['From'] = sender_email
11    message['To'] = recipient_email
12    message['Subject'] = subject
13    
14    # Add body
15    message.attach(MIMEText(body, 'plain'))
16    
17    # Connect to SMTP server and send
18    with smtplib.SMTP('smtp.gmail.com', 587) as server:
19        server.starttls()  # Secure the connection
20        server.login(sender_email, sender_password)
21        server.send_message(message)
22    
23    print(f"Email sent to {recipient_email}")
24
25# Usage
26send_simple_email(
27    sender_email="your.email@gmail.com",
28    sender_password="your_app_password",
29    recipient_email="recipient@example.com",
30    subject="Test Email from Python",
31    body="This is a test email sent using Python!"
32)

Important for Gmail users: Don't use your actual password. Use an App Password:

Go to Google Account settings
Security → 2-Step Verification → App passwords
Generate password for "Mail"
Use this 16-character password in your script

For other email providers:

Outlook/Hotmail: smtp.office365.com, port 587
Yahoo: smtp.mail.yahoo.com, port 587
Custom domain: Check your provider's SMTP settings

Step 2: Secure Credential Storage

Never hardcode passwords in scripts. Use environment variables:

Create `.env` file:

Prompt

EMAIL_ADDRESS=your.email@gmail.com
EMAIL_PASSWORD=your_app_password_here

Load credentials safely:

python

1import os
2from dotenv import load_dotenv
3
4# Load environment variables
5load_dotenv()
6
7EMAIL_ADDRESS = os.getenv('EMAIL_ADDRESS')
8EMAIL_PASSWORD = os.getenv('EMAIL_PASSWORD')
9
10# Now use these instead of hardcoded values

Add .env to .gitignore to prevent accidentally committing credentials!

Step 3: Personalized Bulk Emails

Now let's send personalized emails to multiple recipients from a CSV file.

Sample CSV (`recipients.csv`):

csv

1name,email,company,industry
2John Smith,john@example.com,Acme Corp,Technology
3Sarah Johnson,sarah@example.com,Beta Inc,Healthcare
4Michael Chen,michael@example.com,Gamma LLC,Finance

Bulk email script:

python

1import smtplib
2import pandas as pd
3from email.mime.text import MIMEText
4from email.mime.multipart import MIMEMultipart
5import os
6from dotenv import load_dotenv
7
8load_dotenv()
9
10def send_personalized_email(sender_email, sender_password, recipient_data):
11    """Send personalized email based on recipient data"""
12    
13    # Personalize subject and body
14    subject = f"Exclusive offer for {recipient_data['company']}"
15    
16    body = f"""
17    Hi {recipient_data['name']},
18    
19    I noticed that {recipient_data['company']} is in the {recipient_data['industry']} space, 
20    and I wanted to share something that might interest you.
21    
22    We're helping companies in {recipient_data['industry']} reduce operational costs by 40% 
23    through intelligent automation.
24    
25    Would you be open to a quick 15-minute call next week to explore if this could benefit 
26    {recipient_data['company']}?
27    
28    Best regards,
29    Your Name
30    """
31    
32    # Create message
33    message = MIMEMultipart()
34    message['From'] = sender_email
35    message['To'] = recipient_data['email']
36    message['Subject'] = subject
37    message.attach(MIMEText(body, 'plain'))
38    
39    # Send email
40    try:
41        with smtplib.SMTP('smtp.gmail.com', 587) as server:
42            server.starttls()
43            server.login(sender_email, sender_password)
44            server.send_message(message)
45        
46        print(f"✓ Email sent to {recipient_data['name']} ({recipient_data['email']})")
47        return True
48    
49    except Exception as e:
50        print(f"✗ Failed to send to {recipient_data['email']}: {str(e)}")
51        return False
52
53def send_bulk_emails(csv_file):
54    """Send personalized emails to all recipients in CSV"""
55    
56    # Load recipient data
57    df = pd.read_csv(csv_file)
58    
59    sender_email = os.getenv('EMAIL_ADDRESS')
60    sender_password = os.getenv('EMAIL_PASSWORD')
61    
62    success_count = 0
63    fail_count = 0
64    
65    # Send to each recipient
66    for index, row in df.iterrows():
67        success = send_personalized_email(sender_email, sender_password, row)
68        if success:
69            success_count += 1
70        else:
71            fail_count += 1
72    
73    # Summary
74    print(f"\n{'='*50}")
75    print(f"Campaign complete!")
76    print(f"Successfully sent: {success_count}")
77    print(f"Failed: {fail_count}")
78    print(f"{'='*50}")
79
80# Run the campaign
81send_bulk_emails('recipients.csv')

Output:

Prompt

✓ Email sent to John Smith (john@example.com)
✓ Email sent to Sarah Johnson (sarah@example.com)
✓ Email sent to Michael Chen (michael@example.com)

==================================================
Campaign complete!
Successfully sent: 3
Failed: 0
==================================================

Step 4: HTML Emails with Jinja2 Templates

Plain text is fine, but HTML emails look more professional and allow formatting, images, and buttons.

Create HTML template (`email_template.html`):

html

1<!DOCTYPE html>
2<html>
3<head>
4    <style>
5        body { font-family: Arial, sans-serif; line-height: 1.6; color: #333; }
6        .container { max-width: 600px; margin: 0 auto; padding: 20px; }
7        .header { background: #0066cc; color: white; padding: 20px; text-align: center; }
8        .content { padding: 20px; background: #f9f9f9; }
9        .cta-button { 
10            display: inline-block; 
11            padding: 12px 24px; 
12            background: #0066cc; 
13            color: white; 
14            text-decoration: none; 
15            border-radius: 5px;
16            margin: 20px 0;
17        }
18        .footer { padding: 20px; text-align: center; font-size: 12px; color: #666; }
19    </style>
20</head>
21<body>
22    <div class="container">
23        <div class="header">
24            <h1>Special Offer for {{ company }}</h1>
25        </div>
26        
27        <div class="content">
28            <p>Hi {{ name }},</p>
29            
30            <p>I hope this email finds you well. I'm reaching out because I noticed 
31            {{ company }} is making waves in the {{ industry }} industry.</p>
32            
33            <p>We're helping {{ industry }} companies like yours:</p>
34            <ul>
35                <li>Reduce operational costs by 40%</li>
36                <li>Automate repetitive tasks</li>
37                <li>Scale without hiring</li>
38            </ul>
39            
40            <p>I'd love to show you how {{ company }} could benefit from our platform.</p>
41            
42            <a href="https://calendly.com/your-link" class="cta-button">
43                Schedule a 15-Minute Call
44            </a>
45            
46            <p>Looking forward to connecting,<br>
47            Your Name<br>
48            Your Company</p>
49        </div>
50        
51        <div class="footer">
52            <p>You're receiving this because you signed up at our website.</p>
53            <p><a href="{{ unsubscribe_link }}">Unsubscribe</a></p>
54        </div>
55    </div>
56</body>
57</html>

Send HTML emails with Jinja2:

python

1import smtplib
2from email.mime.text import MIMEText
3from email.mime.multipart import MIMEMultipart
4from jinja2 import Template
5import pandas as pd
6import os
7from dotenv import load_dotenv
8
9load_dotenv()
10
11def send_html_email(sender_email, sender_password, recipient_data, template_file):
12    """Send HTML email using Jinja2 template"""
13    
14    # Load and render template
15    with open(template_file, 'r') as file:
16        template = Template(file.read())
17    
18    html_content = template.render(
19        name=recipient_data['name'],
20        email=recipient_data['email'],
21        company=recipient_data['company'],
22        industry=recipient_data['industry'],
23        unsubscribe_link=f"https://yoursite.com/unsubscribe?email={recipient_data['email']}"
24    )
25    
26    # Create message
27    subject = f"Exclusive automation offer for {recipient_data['company']}"
28    
29    message = MIMEMultipart('alternative')
30    message['From'] = sender_email
31    message['To'] = recipient_data['email']
32    message['Subject'] = subject
33    
34    # Add plain text fallback (for email clients that don't support HTML)
35    text_part = MIMEText(f"Hi {recipient_data['name']}, visit our website for details.", 'plain')
36    html_part = MIMEText(html_content, 'html')
37    
38    message.attach(text_part)
39    message.attach(html_part)
40    
41    # Send
42    try:
43        with smtplib.SMTP('smtp.gmail.com', 587) as server:
44            server.starttls()
45            server.login(sender_email, sender_password)
46            server.send_message(message)
47        
48        print(f"✓ HTML email sent to {recipient_data['name']}")
49        return True
50    
51    except Exception as e:
52        print(f"✗ Failed: {str(e)}")
53        return False
54
55# Usage
56df = pd.read_csv('recipients.csv')
57sender_email = os.getenv('EMAIL_ADDRESS')
58sender_password = os.getenv('EMAIL_PASSWORD')
59
60for _, row in df.iterrows():
61    send_html_email(sender_email, sender_password, row, 'email_template.html')

Step 5: Add Attachments

Send PDFs, images, or documents with your emails.

python

1from email.mime.base import MIMEBase
2from email import encoders
3
4def send_email_with_attachment(sender_email, sender_password, recipient_email, 
5                                subject, body, attachment_path):
6    """Send email with file attachment"""
7    
8    message = MIMEMultipart()
9    message['From'] = sender_email
10    message['To'] = recipient_email
11    message['Subject'] = subject
12    
13    # Add body
14    message.attach(MIMEText(body, 'plain'))
15    
16    # Add attachment
17    with open(attachment_path, 'rb') as attachment:
18        part = MIMEBase('application', 'octet-stream')
19        part.set_payload(attachment.read())
20    
21    encoders.encode_base64(part)
22    
23    # Add header
24    filename = os.path.basename(attachment_path)
25    part.add_header(
26        'Content-Disposition',
27        f'attachment; filename= {filename}'
28    )
29    
30    message.attach(part)
31    
32    # Send
33    with smtplib.SMTP('smtp.gmail.com', 587) as server:
34        server.starttls()
35        server.login(sender_email, sender_password)
36        server.send_message(message)
37    
38    print(f"✓ Email with attachment sent to {recipient_email}")
39
40# Usage
41send_email_with_attachment(
42    sender_email=os.getenv('EMAIL_ADDRESS'),
43    sender_password=os.getenv('EMAIL_PASSWORD'),
44    recipient_email="client@example.com",
45    subject="Your Proposal",
46    body="Please find attached the proposal we discussed.",
47    attachment_path="proposal.pdf"
48)

Multiple attachments:

python

1def send_email_with_multiple_attachments(sender_email, sender_password, recipient_email, 
2                                         subject, body, attachment_paths):
3    """Send email with multiple attachments"""
4    
5    message = MIMEMultipart()
6    message['From'] = sender_email
7    message['To'] = recipient_email
8    message['Subject'] = subject
9    message.attach(MIMEText(body, 'plain'))
10    
11    # Add each attachment
12    for path in attachment_paths:
13        with open(path, 'rb') as file:
14            part = MIMEBase('application', 'octet-stream')
15            part.set_payload(file.read())
16            encoders.encode_base64(part)
17            part.add_header('Content-Disposition', f'attachment; filename= {os.path.basename(path)}')
18            message.attach(part)
19    
20    # Send
21    with smtplib.SMTP('smtp.gmail.com', 587) as server:
22        server.starttls()
23        server.login(sender_email, sender_password)
24        server.send_message(message)
25    
26    print(f"✓ Email with {len(attachment_paths)} attachments sent")
27
28# Usage
29send_email_with_multiple_attachments(
30    sender_email=os.getenv('EMAIL_ADDRESS'),
31    sender_password=os.getenv('EMAIL_PASSWORD'),
32    recipient_email="client@example.com",
33    subject="Project Documents",
34    body="Attached are all the documents we discussed.",
35    attachment_paths=["proposal.pdf", "timeline.xlsx", "mockup.png"]
36)

Step 6: Error Handling and Logging

Production scripts need robust error handling.

python

1import logging
2import time
3from datetime import datetime
4
5# Setup logging
6logging.basicConfig(
7    filename=f'email_campaign_{datetime.now().strftime("%Y%m%d_%H%M%S")}.log',
8    level=logging.INFO,
9    format='%(asctime)s - %(levelname)s - %(message)s'
10)
11
12def send_email_with_retry(sender_email, sender_password, recipient_data, max_retries=3):
13    """Send email with retry logic and logging"""
14    
15    for attempt in range(max_retries):
16        try:
17            # Your email sending code here
18            message = MIMEMultipart()
19            message['From'] = sender_email
20            message['To'] = recipient_data['email']
21            message['Subject'] = f"Message for {recipient_data['name']}"
22            message.attach(MIMEText(f"Hi {recipient_data['name']},\n\nYour message here.", 'plain'))
23            
24            with smtplib.SMTP('smtp.gmail.com', 587, timeout=30) as server:
25                server.starttls()
26                server.login(sender_email, sender_password)
27                server.send_message(message)
28            
29            logging.info(f"SUCCESS: Email sent to {recipient_data['email']}")
30            return True
31        
32        except smtplib.SMTPAuthenticationError:
33            logging.error(f"AUTHENTICATION FAILED: Check credentials")
34            return False  # Don't retry auth failures
35        
36        except smtplib.SMTPRecipientsRefused:
37            logging.error(f"INVALID RECIPIENT: {recipient_data['email']}")
38            return False  # Don't retry invalid emails
39        
40        except (smtplib.SMTPException, ConnectionError) as e:
41            logging.warning(f"ATTEMPT {attempt + 1} FAILED for {recipient_data['email']}: {str(e)}")
42            if attempt < max_retries - 1:
43                wait_time = 2 ** attempt  # Exponential backoff
44                logging.info(f"Retrying in {wait_time} seconds...")
45                time.sleep(wait_time)
46            else:
47                logging.error(f"FAILED after {max_retries} attempts: {recipient_data['email']}")
48                return False
49    
50    return False

Step 7: Rate Limiting to Avoid Spam Filters

Sending too many emails too fast triggers spam filters.

python

1import time
2import random
3
4def send_bulk_with_rate_limit(csv_file, emails_per_minute=20):
5    """Send bulk emails with rate limiting"""
6    
7    df = pd.read_csv(csv_file)
8    sender_email = os.getenv('EMAIL_ADDRESS')
9    sender_password = os.getenv('EMAIL_PASSWORD')
10    
11    delay_seconds = 60 / emails_per_minute
12    
13    for index, row in df.iterrows():
14        send_email_with_retry(sender_email, sender_password, row)
15        
16        # Random delay to appear more human
17        actual_delay = delay_seconds + random.uniform(-0.5, 0.5)
18        print(f"Waiting {actual_delay:.1f} seconds before next email...")
19        time.sleep(actual_delay)
20    
21    print("Campaign complete!")
22
23# Send max 20 emails per minute
24send_bulk_with_rate_limit('recipients.csv', emails_per_minute=20)

Gmail limits:

Free Gmail: 500 emails/day
Google Workspace: 2,000 emails/day
Recommended rate: 20-30 emails/minute max

Step 8: Track Opens and Clicks (Optional)

Track email engagement using tracking pixels and link parameters.

python

1def create_tracked_email(recipient_email, campaign_id):
2    """Add tracking pixel and trackable links"""
3    
4    # Tracking pixel (1x1 transparent image)
5    tracking_url = f"https://yoursite.com/track/open?email={recipient_email}&campaign={campaign_id}"
6    tracking_pixel = f'<img src="{tracking_url}" width="1" height="1" alt="" />'
7    
8    # Trackable link
9    cta_link = f"https://yoursite.com/track/click?email={recipient_email}&campaign={campaign_id}&redirect=https://yoursite.com/offer"
10    
11    html_body = f"""
12    <html>
13        <body>
14            <p>Hi there,</p>
15            <p>Check out our offer:</p>
16            <a href="{cta_link}">Click Here</a>
17            {tracking_pixel}
18        </body>
19    </html>
20    """
21    
22    return html_body

Note: You need a backend server to log these tracking events. Many email platforms (SendGrid, Mailchimp) handle this automatically.

Step 9: Using Professional Email Services

For large-scale campaigns, use dedicated email services:

SendGrid Example:

python

1from sendgrid import SendGridAPIClient
2from sendgrid.helpers.mail import Mail
3
4def send_with_sendgrid(recipient_email, name):
5    message = Mail(
6        from_email='you@yourdomain.com',
7        to_emails=recipient_email,
8        subject=f'Hi {name}',
9        html_content=f'<strong>Hello {name}, this is a personalized message!</strong>'
10    )
11    
12    try:
13        sg = SendGridAPIClient(os.getenv('SENDGRID_API_KEY'))
14        response = sg.send(message)
15        print(f"Email sent! Status code: {response.status_code}")
16    except Exception as e:
17        print(f"Error: {str(e)}")

Why use email services?

Higher deliverability rates
Better spam filter avoidance
Built-in analytics and tracking
Handle bounces and unsubscribes
Scale to millions of emails

Popular options:

SendGrid: 100 emails/day free
Mailgun: 5,000 emails/month free
Amazon SES: $0.10 per 1,000 emails

Best Practices for Deliverability

1. Authenticate your domain:

Set up SPF, DKIM, and DMARC records
Use a custom domain (not @gmail.com for business emails)

2. Warm up your sending:

Start with 20-50 emails/day
Gradually increase over 2-3 weeks
Don't go from 0 to 1,000 emails overnight

3. Maintain list hygiene:

Remove bounced emails
Honor unsubscribe requests immediately
Don't buy email lists

4. Write good subject lines:

Avoid spam trigger words: "FREE," "ACT NOW," "LIMITED TIME"
Keep under 50 characters
Personalize when possible

5. Include unsubscribe option:

Required by law (CAN-SPAM Act)
Shows you're legitimate
Improves deliverability

Frequently Asked Questions

Is it legal to send bulk emails? Yes, if you follow anti-spam laws (CAN-SPAM in US, GDPR in EU). Key requirements: recipients opted in, include unsubscribe link, use accurate from address, honor unsubscribe requests.

How many emails can I send with Gmail? 500/day for free Gmail, 2,000/day for Google Workspace. For more, use dedicated email services.

Will my emails go to spam? Possibly, especially if you're new to bulk sending. Follow best practices: authenticate domain, warm up sending, write good content, avoid spam triggers, maintain list hygiene.

Can I schedule emails to send later? Yes, use Python's schedule library or task schedulers (cron, Task Scheduler). Or use time.sleep() for simple delays.

How do I handle unsubscribes? Maintain an unsubscribe list. Before sending, check if recipient is on that list. Skip sending if they are. Most email services handle this automatically.

The Bottom Line

Python email automation transforms tedious manual email tasks into automated workflows. Whether you're sending 50 emails or 50,000, the script does the work while you focus on strategy.

Key takeaways:

Use environment variables for credentials (never hardcode)
Personalize with Jinja2 templates for professional HTML emails
Implement error handling and retry logic
Respect rate limits (20-30 emails/minute max)
Track success/failure with logging
For scale, use professional email services (SendGrid, Mailgun)

Start with the simple script. Send 10 test emails. Then scale up. Within an hour, you'll have a system that handles email campaigns automatically, personalized, and professionally.

Your future self will thank you every time you'd otherwise be manually sending emails.

Python Email Automation: Send Personalized Emails at Scale

Email automation with Python isn't just about bulk sending. It's about personalizing at scale—making each recipient feel like you wrote specifically to them, even when you're sending to thousands.

Let me show you how to build a production-ready email automation system with Python.

What You'll Learn

By the end of this tutorial, you'll be able to:

Send personalized emails to hundreds of recipients
Pull recipient data from CSV, Excel, or databases
Customize email content based on recipient attributes
Handle attachments (PDFs, images, documents)
Track email delivery and handle failures
Avoid spam filters and maintain deliverability
Schedule automated email campaigns

All with Python and free/low-cost tools.

Prerequisites

What you need:

Python 3.8+ installed
Basic Python knowledge (loops, functions, string formatting)
An email account (Gmail, Outlook, or SMTP service)
20-30 minutes

Libraries we'll use:

smtplib (built-in, sends emails via SMTP)
email (built-in, constructs email messages)
pandas (data handling)
jinja2 (email templating)
python-dotenv (secure credential storage)

Step 1: Setup and Simple Email

First, let's send a single email to understand the basics.

Install dependencies:

bash

1pip install pandas jinja2 python-dotenv openpyxl

Create your first email script:

python

1import smtplib
2from email.mime.text import MIMEText
3from email.mime.multipart import MIMEMultipart
4
5def send_simple_email(sender_email, sender_password, recipient_email, subject, body):
6    """Send a plain text email"""
7    
8    # Create message
9    message = MIMEMultipart()
10    message['From'] = sender_email
11    message['To'] = recipient_email
12    message['Subject'] = subject
13    
14    # Add body
15    message.attach(MIMEText(body, 'plain'))
16    
17    # Connect to SMTP server and send
18    with smtplib.SMTP('smtp.gmail.com', 587) as server:
19        server.starttls()  # Secure the connection
20        server.login(sender_email, sender_password)
21        server.send_message(message)
22    
23    print(f"Email sent to {recipient_email}")
24
25# Usage
26send_simple_email(
27    sender_email="your.email@gmail.com",
28    sender_password="your_app_password",
29    recipient_email="recipient@example.com",
30    subject="Test Email from Python",
31    body="This is a test email sent using Python!"
32)

Important for Gmail users: Don't use your actual password. Use an App Password:

Go to Google Account settings
Security → 2-Step Verification → App passwords
Generate password for "Mail"
Use this 16-character password in your script

For other email providers:

Outlook/Hotmail: smtp.office365.com, port 587
Yahoo: smtp.mail.yahoo.com, port 587
Custom domain: Check your provider's SMTP settings

Step 2: Secure Credential Storage

Never hardcode passwords in scripts. Use environment variables:

Create `.env` file:

Prompt

EMAIL_ADDRESS=your.email@gmail.com
EMAIL_PASSWORD=your_app_password_here

Load credentials safely:

python

1import os
2from dotenv import load_dotenv
3
4# Load environment variables
5load_dotenv()
6
7EMAIL_ADDRESS = os.getenv('EMAIL_ADDRESS')
8EMAIL_PASSWORD = os.getenv('EMAIL_PASSWORD')
9
10# Now use these instead of hardcoded values

Add .env to .gitignore to prevent accidentally committing credentials!

Step 3: Personalized Bulk Emails

Now let's send personalized emails to multiple recipients from a CSV file.

Sample CSV (`recipients.csv`):

csv

1name,email,company,industry
2John Smith,john@example.com,Acme Corp,Technology
3Sarah Johnson,sarah@example.com,Beta Inc,Healthcare
4Michael Chen,michael@example.com,Gamma LLC,Finance

Bulk email script:

python

1import smtplib
2import pandas as pd
3from email.mime.text import MIMEText
4from email.mime.multipart import MIMEMultipart
5import os
6from dotenv import load_dotenv
7
8load_dotenv()
9
10def send_personalized_email(sender_email, sender_password, recipient_data):
11    """Send personalized email based on recipient data"""
12    
13    # Personalize subject and body
14    subject = f"Exclusive offer for {recipient_data['company']}"
15    
16    body = f"""
17    Hi {recipient_data['name']},
18    
19    I noticed that {recipient_data['company']} is in the {recipient_data['industry']} space, 
20    and I wanted to share something that might interest you.
21    
22    We're helping companies in {recipient_data['industry']} reduce operational costs by 40% 
23    through intelligent automation.
24    
25    Would you be open to a quick 15-minute call next week to explore if this could benefit 
26    {recipient_data['company']}?
27    
28    Best regards,
29    Your Name
30    """
31    
32    # Create message
33    message = MIMEMultipart()
34    message['From'] = sender_email
35    message['To'] = recipient_data['email']
36    message['Subject'] = subject
37    message.attach(MIMEText(body, 'plain'))
38    
39    # Send email
40    try:
41        with smtplib.SMTP('smtp.gmail.com', 587) as server:
42            server.starttls()
43            server.login(sender_email, sender_password)
44            server.send_message(message)
45        
46        print(f"✓ Email sent to {recipient_data['name']} ({recipient_data['email']})")
47        return True
48    
49    except Exception as e:
50        print(f"✗ Failed to send to {recipient_data['email']}: {str(e)}")
51        return False
52
53def send_bulk_emails(csv_file):
54    """Send personalized emails to all recipients in CSV"""
55    
56    # Load recipient data
57    df = pd.read_csv(csv_file)
58    
59    sender_email = os.getenv('EMAIL_ADDRESS')
60    sender_password = os.getenv('EMAIL_PASSWORD')
61    
62    success_count = 0
63    fail_count = 0
64    
65    # Send to each recipient
66    for index, row in df.iterrows():
67        success = send_personalized_email(sender_email, sender_password, row)
68        if success:
69            success_count += 1
70        else:
71            fail_count += 1
72    
73    # Summary
74    print(f"\n{'='*50}")
75    print(f"Campaign complete!")
76    print(f"Successfully sent: {success_count}")
77    print(f"Failed: {fail_count}")
78    print(f"{'='*50}")
79
80# Run the campaign
81send_bulk_emails('recipients.csv')

Output:

Prompt

✓ Email sent to John Smith (john@example.com)
✓ Email sent to Sarah Johnson (sarah@example.com)
✓ Email sent to Michael Chen (michael@example.com)

==================================================
Campaign complete!
Successfully sent: 3
Failed: 0
==================================================

Step 4: HTML Emails with Jinja2 Templates

Plain text is fine, but HTML emails look more professional and allow formatting, images, and buttons.

Create HTML template (`email_template.html`):

html

1<!DOCTYPE html>
2<html>
3<head>
4    <style>
5        body { font-family: Arial, sans-serif; line-height: 1.6; color: #333; }
6        .container { max-width: 600px; margin: 0 auto; padding: 20px; }
7        .header { background: #0066cc; color: white; padding: 20px; text-align: center; }
8        .content { padding: 20px; background: #f9f9f9; }
9        .cta-button { 
10            display: inline-block; 
11            padding: 12px 24px; 
12            background: #0066cc; 
13            color: white; 
14            text-decoration: none; 
15            border-radius: 5px;
16            margin: 20px 0;
17        }
18        .footer { padding: 20px; text-align: center; font-size: 12px; color: #666; }
19    </style>
20</head>
21<body>
22    <div class="container">
23        <div class="header">
24            <h1>Special Offer for {{ company }}</h1>
25        </div>
26        
27        <div class="content">
28            <p>Hi {{ name }},</p>
29            
30            <p>I hope this email finds you well. I'm reaching out because I noticed 
31            {{ company }} is making waves in the {{ industry }} industry.</p>
32            
33            <p>We're helping {{ industry }} companies like yours:</p>
34            <ul>
35                <li>Reduce operational costs by 40%</li>
36                <li>Automate repetitive tasks</li>
37                <li>Scale without hiring</li>
38            </ul>
39            
40            <p>I'd love to show you how {{ company }} could benefit from our platform.</p>
41            
42            <a href="https://calendly.com/your-link" class="cta-button">
43                Schedule a 15-Minute Call
44            </a>
45            
46            <p>Looking forward to connecting,<br>
47            Your Name<br>
48            Your Company</p>
49        </div>
50        
51        <div class="footer">
52            <p>You're receiving this because you signed up at our website.</p>
53            <p><a href="{{ unsubscribe_link }}">Unsubscribe</a></p>
54        </div>
55    </div>
56</body>
57</html>

Send HTML emails with Jinja2:

python

1import smtplib
2from email.mime.text import MIMEText
3from email.mime.multipart import MIMEMultipart
4from jinja2 import Template
5import pandas as pd
6import os
7from dotenv import load_dotenv
8
9load_dotenv()
10
11def send_html_email(sender_email, sender_password, recipient_data, template_file):
12    """Send HTML email using Jinja2 template"""
13    
14    # Load and render template
15    with open(template_file, 'r') as file:
16        template = Template(file.read())
17    
18    html_content = template.render(
19        name=recipient_data['name'],
20        email=recipient_data['email'],
21        company=recipient_data['company'],
22        industry=recipient_data['industry'],
23        unsubscribe_link=f"https://yoursite.com/unsubscribe?email={recipient_data['email']}"
24    )
25    
26    # Create message
27    subject = f"Exclusive automation offer for {recipient_data['company']}"
28    
29    message = MIMEMultipart('alternative')
30    message['From'] = sender_email
31    message['To'] = recipient_data['email']
32    message['Subject'] = subject
33    
34    # Add plain text fallback (for email clients that don't support HTML)
35    text_part = MIMEText(f"Hi {recipient_data['name']}, visit our website for details.", 'plain')
36    html_part = MIMEText(html_content, 'html')
37    
38    message.attach(text_part)
39    message.attach(html_part)
40    
41    # Send
42    try:
43        with smtplib.SMTP('smtp.gmail.com', 587) as server:
44            server.starttls()
45            server.login(sender_email, sender_password)
46            server.send_message(message)
47        
48        print(f"✓ HTML email sent to {recipient_data['name']}")
49        return True
50    
51    except Exception as e:
52        print(f"✗ Failed: {str(e)}")
53        return False
54
55# Usage
56df = pd.read_csv('recipients.csv')
57sender_email = os.getenv('EMAIL_ADDRESS')
58sender_password = os.getenv('EMAIL_PASSWORD')
59
60for _, row in df.iterrows():
61    send_html_email(sender_email, sender_password, row, 'email_template.html')

Step 5: Add Attachments

Send PDFs, images, or documents with your emails.

python

1from email.mime.base import MIMEBase
2from email import encoders
3
4def send_email_with_attachment(sender_email, sender_password, recipient_email, 
5                                subject, body, attachment_path):
6    """Send email with file attachment"""
7    
8    message = MIMEMultipart()
9    message['From'] = sender_email
10    message['To'] = recipient_email
11    message['Subject'] = subject
12    
13    # Add body
14    message.attach(MIMEText(body, 'plain'))
15    
16    # Add attachment
17    with open(attachment_path, 'rb') as attachment:
18        part = MIMEBase('application', 'octet-stream')
19        part.set_payload(attachment.read())
20    
21    encoders.encode_base64(part)
22    
23    # Add header
24    filename = os.path.basename(attachment_path)
25    part.add_header(
26        'Content-Disposition',
27        f'attachment; filename= {filename}'
28    )
29    
30    message.attach(part)
31    
32    # Send
33    with smtplib.SMTP('smtp.gmail.com', 587) as server:
34        server.starttls()
35        server.login(sender_email, sender_password)
36        server.send_message(message)
37    
38    print(f"✓ Email with attachment sent to {recipient_email}")
39
40# Usage
41send_email_with_attachment(
42    sender_email=os.getenv('EMAIL_ADDRESS'),
43    sender_password=os.getenv('EMAIL_PASSWORD'),
44    recipient_email="client@example.com",
45    subject="Your Proposal",
46    body="Please find attached the proposal we discussed.",
47    attachment_path="proposal.pdf"
48)

Multiple attachments:

python

1def send_email_with_multiple_attachments(sender_email, sender_password, recipient_email, 
2                                         subject, body, attachment_paths):
3    """Send email with multiple attachments"""
4    
5    message = MIMEMultipart()
6    message['From'] = sender_email
7    message['To'] = recipient_email
8    message['Subject'] = subject
9    message.attach(MIMEText(body, 'plain'))
10    
11    # Add each attachment
12    for path in attachment_paths:
13        with open(path, 'rb') as file:
14            part = MIMEBase('application', 'octet-stream')
15            part.set_payload(file.read())
16            encoders.encode_base64(part)
17            part.add_header('Content-Disposition', f'attachment; filename= {os.path.basename(path)}')
18            message.attach(part)
19    
20    # Send
21    with smtplib.SMTP('smtp.gmail.com', 587) as server:
22        server.starttls()
23        server.login(sender_email, sender_password)
24        server.send_message(message)
25    
26    print(f"✓ Email with {len(attachment_paths)} attachments sent")
27
28# Usage
29send_email_with_multiple_attachments(
30    sender_email=os.getenv('EMAIL_ADDRESS'),
31    sender_password=os.getenv('EMAIL_PASSWORD'),
32    recipient_email="client@example.com",
33    subject="Project Documents",
34    body="Attached are all the documents we discussed.",
35    attachment_paths=["proposal.pdf", "timeline.xlsx", "mockup.png"]
36)

Step 6: Error Handling and Logging

Production scripts need robust error handling.

python

1import logging
2import time
3from datetime import datetime
4
5# Setup logging
6logging.basicConfig(
7    filename=f'email_campaign_{datetime.now().strftime("%Y%m%d_%H%M%S")}.log',
8    level=logging.INFO,
9    format='%(asctime)s - %(levelname)s - %(message)s'
10)
11
12def send_email_with_retry(sender_email, sender_password, recipient_data, max_retries=3):
13    """Send email with retry logic and logging"""
14    
15    for attempt in range(max_retries):
16        try:
17            # Your email sending code here
18            message = MIMEMultipart()
19            message['From'] = sender_email
20            message['To'] = recipient_data['email']
21            message['Subject'] = f"Message for {recipient_data['name']}"
22            message.attach(MIMEText(f"Hi {recipient_data['name']},\n\nYour message here.", 'plain'))
23            
24            with smtplib.SMTP('smtp.gmail.com', 587, timeout=30) as server:
25                server.starttls()
26                server.login(sender_email, sender_password)
27                server.send_message(message)
28            
29            logging.info(f"SUCCESS: Email sent to {recipient_data['email']}")
30            return True
31        
32        except smtplib.SMTPAuthenticationError:
33            logging.error(f"AUTHENTICATION FAILED: Check credentials")
34            return False  # Don't retry auth failures
35        
36        except smtplib.SMTPRecipientsRefused:
37            logging.error(f"INVALID RECIPIENT: {recipient_data['email']}")
38            return False  # Don't retry invalid emails
39        
40        except (smtplib.SMTPException, ConnectionError) as e:
41            logging.warning(f"ATTEMPT {attempt + 1} FAILED for {recipient_data['email']}: {str(e)}")
42            if attempt < max_retries - 1:
43                wait_time = 2 ** attempt  # Exponential backoff
44                logging.info(f"Retrying in {wait_time} seconds...")
45                time.sleep(wait_time)
46            else:
47                logging.error(f"FAILED after {max_retries} attempts: {recipient_data['email']}")
48                return False
49    
50    return False

Step 7: Rate Limiting to Avoid Spam Filters

Sending too many emails too fast triggers spam filters.

python

1import time
2import random
3
4def send_bulk_with_rate_limit(csv_file, emails_per_minute=20):
5    """Send bulk emails with rate limiting"""
6    
7    df = pd.read_csv(csv_file)
8    sender_email = os.getenv('EMAIL_ADDRESS')
9    sender_password = os.getenv('EMAIL_PASSWORD')
10    
11    delay_seconds = 60 / emails_per_minute
12    
13    for index, row in df.iterrows():
14        send_email_with_retry(sender_email, sender_password, row)
15        
16        # Random delay to appear more human
17        actual_delay = delay_seconds + random.uniform(-0.5, 0.5)
18        print(f"Waiting {actual_delay:.1f} seconds before next email...")
19        time.sleep(actual_delay)
20    
21    print("Campaign complete!")
22
23# Send max 20 emails per minute
24send_bulk_with_rate_limit('recipients.csv', emails_per_minute=20)

Gmail limits:

Free Gmail: 500 emails/day
Google Workspace: 2,000 emails/day
Recommended rate: 20-30 emails/minute max

Step 8: Track Opens and Clicks (Optional)

Track email engagement using tracking pixels and link parameters.

python

1def create_tracked_email(recipient_email, campaign_id):
2    """Add tracking pixel and trackable links"""
3    
4    # Tracking pixel (1x1 transparent image)
5    tracking_url = f"https://yoursite.com/track/open?email={recipient_email}&campaign={campaign_id}"
6    tracking_pixel = f'<img src="{tracking_url}" width="1" height="1" alt="" />'
7    
8    # Trackable link
9    cta_link = f"https://yoursite.com/track/click?email={recipient_email}&campaign={campaign_id}&redirect=https://yoursite.com/offer"
10    
11    html_body = f"""
12    <html>
13        <body>
14            <p>Hi there,</p>
15            <p>Check out our offer:</p>
16            <a href="{cta_link}">Click Here</a>
17            {tracking_pixel}
18        </body>
19    </html>
20    """
21    
22    return html_body

Note: You need a backend server to log these tracking events. Many email platforms (SendGrid, Mailchimp) handle this automatically.

Step 9: Using Professional Email Services

For large-scale campaigns, use dedicated email services:

SendGrid Example:

python

1from sendgrid import SendGridAPIClient
2from sendgrid.helpers.mail import Mail
3
4def send_with_sendgrid(recipient_email, name):
5    message = Mail(
6        from_email='you@yourdomain.com',
7        to_emails=recipient_email,
8        subject=f'Hi {name}',
9        html_content=f'<strong>Hello {name}, this is a personalized message!</strong>'
10    )
11    
12    try:
13        sg = SendGridAPIClient(os.getenv('SENDGRID_API_KEY'))
14        response = sg.send(message)
15        print(f"Email sent! Status code: {response.status_code}")
16    except Exception as e:
17        print(f"Error: {str(e)}")

Why use email services?

Higher deliverability rates
Better spam filter avoidance
Built-in analytics and tracking
Handle bounces and unsubscribes
Scale to millions of emails

Popular options:

SendGrid: 100 emails/day free
Mailgun: 5,000 emails/month free
Amazon SES: $0.10 per 1,000 emails

Best Practices for Deliverability

1. Authenticate your domain:

Set up SPF, DKIM, and DMARC records
Use a custom domain (not @gmail.com for business emails)

2. Warm up your sending:

Start with 20-50 emails/day
Gradually increase over 2-3 weeks
Don't go from 0 to 1,000 emails overnight

3. Maintain list hygiene:

Remove bounced emails
Honor unsubscribe requests immediately
Don't buy email lists

4. Write good subject lines:

Avoid spam trigger words: "FREE," "ACT NOW," "LIMITED TIME"
Keep under 50 characters
Personalize when possible

5. Include unsubscribe option:

Required by law (CAN-SPAM Act)
Shows you're legitimate
Improves deliverability

Frequently Asked Questions

How many emails can I send with Gmail? 500/day for free Gmail, 2,000/day for Google Workspace. For more, use dedicated email services.

Can I schedule emails to send later? Yes, use Python's schedule library or task schedulers (cron, Task Scheduler). Or use time.sleep() for simple delays.

How do I handle unsubscribes? Maintain an unsubscribe list. Before sending, check if recipient is on that list. Skip sending if they are. Most email services handle this automatically.

The Bottom Line

Python email automation transforms tedious manual email tasks into automated workflows. Whether you're sending 50 emails or 50,000, the script does the work while you focus on strategy.

Key takeaways:

Use environment variables for credentials (never hardcode)
Personalize with Jinja2 templates for professional HTML emails
Implement error handling and retry logic
Respect rate limits (20-30 emails/minute max)
Track success/failure with logging
For scale, use professional email services (SendGrid, Mailgun)

Start with the simple script. Send 10 test emails. Then scale up. Within an hour, you'll have a system that handles email campaigns automatically, personalized, and professionally.

Your future self will thank you every time you'd otherwise be manually sending emails.

Python Email Automation: Send Personalized Emails at Scale

What You'll Learn

Prerequisites

Step 1: Setup and Simple Email

Install dependencies:

Create your first email script:

Step 2: Secure Credential Storage

Create .env file:

Load credentials safely:

Step 3: Personalized Bulk Emails

Sample CSV (recipients.csv):

Bulk email script:

Step 4: HTML Emails with Jinja2 Templates

Create HTML template (email_template.html):

Send HTML emails with Jinja2:

Step 5: Add Attachments

Step 6: Error Handling and Logging

Step 7: Rate Limiting to Avoid Spam Filters

Step 8: Track Opens and Clicks (Optional)

Step 9: Using Professional Email Services

SendGrid Example:

Best Practices for Deliverability

Frequently Asked Questions

The Bottom Line

Share this article

Python Email Automation: Send Personalized Emails at Scale

What You'll Learn

Prerequisites

Step 1: Setup and Simple Email

Install dependencies:

Create your first email script:

Step 2: Secure Credential Storage

Create .env file:

Load credentials safely:

Step 3: Personalized Bulk Emails

Sample CSV (recipients.csv):

Bulk email script:

Step 4: HTML Emails with Jinja2 Templates

Create HTML template (email_template.html):

Send HTML emails with Jinja2:

Step 5: Add Attachments

Step 6: Error Handling and Logging

Step 7: Rate Limiting to Avoid Spam Filters

Step 8: Track Opens and Clicks (Optional)

Step 9: Using Professional Email Services

SendGrid Example:

Best Practices for Deliverability

Frequently Asked Questions

The Bottom Line

Share this article

Create `.env` file:

Sample CSV (`recipients.csv`):

Create HTML template (`email_template.html`):

Create `.env` file:

Sample CSV (`recipients.csv`):

Create HTML template (`email_template.html`):