Send Emails with Python: smtplib, MIME and Attachments

Send Emails with Python: smtplib, MIME and Attachments

Python's smtplib and email modules let you send emails from any SMTP provider: Gmail, Outlook, SendGrid, or your own server. Supports plain text, HTML, and file attachments.

Simple Text Email with smtplib

import smtplib
from email.mime.text import MIMEText

def send_email(to, subject, body, sender, password,
               smtp_host="smtp.gmail.com", smtp_port=587):
    msg = MIMEText(body, "plain", "utf-8")
    msg["Subject"] = subject
    msg["From"]    = sender
    msg["To"]      = to

    with smtplib.SMTP(smtp_host, smtp_port) as server:
        server.ehlo()
        server.starttls()
        server.login(sender, password)
        server.sendmail(sender, [to], msg.as_string())
    print(f"Email sent to {to}")

# Gmail: use an App Password (not your account password)
send_email(
    to="customer@example.com",
    subject="Your order is ready",
    body="Hello,\n\nYour order has been processed successfully.\n\nBest regards.",
    sender="mybusiness@gmail.com",
    password="abcd efgh ijkl mnop"  # 16-character app password
)

HTML Email with Plain Text Fallback

import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText

def send_html_email(to, subject, html, plain_text, sender, password):
    msg = MIMEMultipart("alternative")
    msg["Subject"] = subject
    msg["From"]    = sender
    msg["To"]      = to

    msg.attach(MIMEText(plain_text, "plain", "utf-8"))
    msg.attach(MIMEText(html,       "html",  "utf-8"))

    with smtplib.SMTP("smtp.gmail.com", 587) as s:
        s.starttls()
        s.login(sender, password)
        s.sendmail(sender, [to], msg.as_string())
    print(f"HTML email sent to {to}")

html = """
<html><body>
  <h2 style="color:#4a9eff">Your Order #1234</h2>
  <p>Your order has been <strong>confirmed</strong> and is on its way.</p>
  <a href="https://mystore.com/orders/1234" style="background:#4a9eff;color:white;padding:10px 20px;text-decoration:none;border-radius:4px">View Order</a>
</body></html>
"""
plain = "Your order #1234 has been confirmed.\nView: https://mystore.com/orders/1234"
send_html_email("customer@example.com", "Order Confirmed", html, plain,
                "mystore@gmail.com", "app_password")

Send with File Attachments

import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from email.mime.base import MIMEBase
from email import encoders
import os

def send_with_attachments(to, subject, body, attachment_paths, sender, password):
    msg = MIMEMultipart()
    msg["Subject"] = subject
    msg["From"]    = sender
    msg["To"]      = to
    msg.attach(MIMEText(body, "plain", "utf-8"))

    for path in attachment_paths:
        with open(path, "rb") as f:
            part = MIMEBase("application", "octet-stream")
            part.set_payload(f.read())
        encoders.encode_base64(part)
        name = os.path.basename(path)
        part.add_header("Content-Disposition", f'attachment; filename="{name}"')
        msg.attach(part)

    with smtplib.SMTP("smtp.gmail.com", 587) as s:
        s.starttls()
        s.login(sender, password)
        s.sendmail(sender, [to], msg.as_string())
    print(f"Email with {len(attachment_paths)} attachments sent to {to}")

send_with_attachments(
    "customer@example.com",
    "Your Invoice",
    "Please find your invoice attached.",
    ["invoice_april.pdf", "summary.xlsx"],
    "mybusiness@gmail.com",
    "app_password"
)

Bulk Mailing from CSV Template

import smtplib
from email.mime.text import MIMEText
import csv

def bulk_mail(csv_contacts, subject_tpl, body_tpl, sender, password):
    with open(csv_contacts, encoding="utf-8") as f:
        contacts = list(csv.DictReader(f))  # columns: name, email

    sent = 0
    with smtplib.SMTP("smtp.gmail.com", 587) as server:
        server.starttls()
        server.login(sender, password)
        for c in contacts:
            subject = subject_tpl.replace("{name}", c["name"])
            body    = body_tpl.replace("{name}", c["name"])
            msg = MIMEText(body, "plain", "utf-8")
            msg["Subject"] = subject
            msg["From"]    = sender
            msg["To"]      = c["email"]
            try:
                server.sendmail(sender, [c["email"]], msg.as_string())
                sent += 1
                print(f"  [{sent}] Sent to {c['email']}")
            except Exception as e:
                print(f"  ERROR {c['email']}: {e}")

    print(f"Total sent: {sent}/{len(contacts)}")

bulk_mail(
    "customers.csv",
    "Hi {name}, we have news for you",
    "Hi {name},\n\nWe're reaching out with some exciting updates.\n\nBest regards.",
    "newsletter@mycompany.com",
    "app_password"
)

SMTP Provider Reference

Additional Resource

For converting email attachments between PDF, DOCX, JPG and other formats without any coding, use KaijuConverter — free and no registration required.

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