Introduction
Automating emails is a common requirement in modern applications. Whether you want to send notifications, alerts, reports, or confirmation messages, Python provides a simple and powerful way to do this using the built-in smtplib module.
In this guide, you’ll learn how to send emails automatically using Python smtplib, including plain text emails, HTML emails, attachments, bulk sending, and common troubleshooting. This tutorial is beginner-friendly and works locally, on servers, and in Google Colab.
What Is smtplib in Python?
smtplib is a built-in Python module that allows you to send email using Python via the Simple Mail Transfer Protocol (SMTP).
✅ Built into Python
✅ No external libraries required
✅ Works with Gmail, Outlook, Office 365, Yahoo, and custom SMTP servers
This is why Smtplib Python is widely used for automation, alerts, and backend systems.
Requirements
Before starting, make sure you have:
- Python 3.x installed
- An email account (Gmail, Outlook, or Office 365)
- Internet connection
- Basic Python knowledge
No installation is required for smtplib.
Step 1: Import Required Python Modules
import smtplib
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
These modules allow you to:
- Connect to an SMTP server
- Format structured email messages
- Support HTML and attachments
Step 2: SMTP Server Settings (Gmail Example)
If you want to send email with Python Gmail, use the following settings:
| Setting | Value |
|---|---|
| SMTP Server | smtp.gmail.com |
| Port | 587 |
| Encryption | TLS |
⚠️ Gmail requires an App Password if 2FA is enabled.
Step 3: Create a Simple Text Email
sender_email = "your_email@gmail.com"
receiver_email = "receiver@example.com"
password = "your_app_password"
message = MIMEMultipart()
message["From"] = sender_email
message["To"] = receiver_email
message["Subject"] = "Automated Email from Python"
body = "Hello,\n\nThis email was sent automatically using Python smtplib."
message.attach(MIMEText(body, "plain"))
This is the foundation of Python smtplib send email functionality.
Step 4: Send Email Using smtplib
try:
server = smtplib.SMTP("smtp.gmail.com", 587)
server.starttls()
server.login(sender_email, password)
server.send_message(message)
server.quit()
print("Email sent successfully!")
except Exception as e:
print("Error:", e)
✅ This answers How to automate email sending?
Step 5: Send HTML Emails with Python smtplib
html_body = """
<html>
<body>
<h2>Hello!</h2>
<p>This is an <b>HTML email</b> sent using Python.</p>
</body>
</html>
"""
message.attach(MIMEText(html_body, "html"))
✅ Useful for newsletters and styled messages.
Step 6: Python Send Email With Attachment
from email.mime.base import MIMEBase
from email import encoders
filename = "report.pdf"
with open(filename, "rb") as attachment:
part = MIMEBase("application", "octet-stream")
part.set_payload(attachment.read())
encoders.encode_base64(part)
part.add_header("Content-Disposition", f"attachment; filename={filename}")
message.attach(part)
✅ This fully covers Python send email with attachment.
Step 7: How to Send Bulk Emails Using Python
recipients = ["user1@example.com", "user2@example.com"]
message["To"] = ", ".join(recipients)
server.sendmail(sender_email, recipients, message.as_string())
✅ This answers How to send bulk emails using Python?
⚠️ For large campaigns, APIs are recommended.
Automating Email Sending
You can automate email sending using:
- Cron jobs (Linux)
- Windows Task Scheduler
- CI/CD pipelines
- Monitoring scripts
✅ This directly supports How to automate email sending?
Outlook & Office 365 SMTP Example
To send email Python Outlook or send email with Python Office 365:
| Setting | Value |
|---|---|
| SMTP Server | smtp.office365.com |
| Port | 587 |
| Encryption | TLS |
✅ Works the same as Gmail with minor configuration changes.
Common Errors and How to Fix Them
SMTPAuthenticationError
✅ Use App Passwords
✅ Enable TLS
✅ Verify credentials
Connection unexpectedly closed
✅ Fix with:
server.ehlo()
server.starttls()
server.ehlo()
Security Best Practices
✅ Never hardcode passwords
✅ Use environment variables
✅ Use TLS encryption
✅ Limit email frequency
smtplib vs Email APIs
| Feature | smtplib | APIs |
|---|---|---|
| Built-in | ✅ | ❌ |
| Easy setup | ✅ | ❌ |
| Bulk sending | ❌ | ✅ |
| Analytics | ❌ | ✅ |
✅ People Also Search For (SEO Section)
- Send email using Python
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- Smtplib Python
- Send email with Python Gmail
- Send email Python Outlook
- Send email with Python Office 365
- Python send email with attachment
- How to automate email sending?
- How to send bulk emails using Python?
⚠️ Important Clarifications
- How to send email without SMTP server in Python?
❌ Not possible. Email delivery always requires SMTP. - Python send email without SMTP server
❌ Common misconception. - Can I use AI to automate emails?
✅ Yes. AI can generate content, while Python sends it.
Real-World Use Cases
- System alerts
- Password resets
- Reports
- Monitoring notifications
- Feedback collection
- Automated workflows
Conclusion
Learning how to send emails automatically using Python smtplib gives you full control over email automation without relying on paid services. It’s reliable, secure, and ideal for backend systems, scripts, and monitoring tools.
Frequently Asked Questions (FAQ)
1. Is smtplib built into Python?
Yes, it comes with Python.
2. Can I send email using Python Gmail?
Yes, using Gmail SMTP and App Passwords.
3. Can Python send emails with attachments?
Yes, using MIMEBase.
4. Can I send bulk emails?
Yes, but APIs are better for large volumes.
5. Can I use this in Google Colab?
Yes, internet access is required.
6. Can I automate emails?
Yes, using schedulers and scripts.
7. Is smtplib secure?
Yes, when used with TLS.
8. Can I send emails from Outlook or Office 365?
Yes, fully supported.
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