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This guide covers SMTP integration. For full configuration options and available headers, see the SMTP Introduction.

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Basic Configuration

Use environment variables for credentials: 
import os

SMTP_HOST = 'smtp.lettermint.co'
SMTP_USERNAME = 'lettermint'
API_TOKEN = os.environ.get('LETTERMINT_API_TOKEN')

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

# SMTP configuration
SMTP_HOST = 'smtp.lettermint.co'
SMTP_PORT = 587
USERNAME = 'lettermint'
API_TOKEN = os.environ.get('LETTERMINT_API_TOKEN')

def send_email(to_email, subject, html_body, text_body=None):
    msg = MIMEMultipart('alternative')
    msg['From'] = 'sender@yourdomain.com'
    msg['To'] = to_email
    msg['Subject'] = subject

    if text_body:
        msg.attach(MIMEText(text_body, 'plain'))
    msg.attach(MIMEText(html_body, 'html'))

    try:
        with smtplib.SMTP(SMTP_HOST, SMTP_PORT) as server:
            server.starttls()
            server.login(USERNAME, API_TOKEN)
            server.send_message(msg)
        print("Email sent successfully")
    except Exception as e:
        print(f"Error sending email: {e}")

send_email(
    to_email='recipient@example.com',
    subject='Test Email',
    html_body='<h1>Hello!</h1><p>This is a test email.</p>',
    text_body='Hello! This is a test email.'
)

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Advanced Features

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Multiple Recipients

def send_bulk_email(recipients, subject, html_body):
    msg = MIMEMultipart('alternative')
    msg['From'] = 'sender@yourdomain.com'
    msg['Subject'] = subject
    msg.attach(MIMEText(html_body, 'html'))

    with smtplib.SMTP(SMTP_HOST, SMTP_PORT) as server:
        server.starttls()
        server.login(USERNAME, API_TOKEN)

        for recipient in recipients:
            msg['To'] = recipient
            server.send_message(msg)
            del msg['To']  # Remove for next iteration

​
Attachments

def send_email_with_attachment(to_email, subject, body, file_path):
    msg = MIMEMultipart()
    msg['From'] = 'sender@yourdomain.com'
    msg['To'] = to_email
    msg['Subject'] = subject

    msg.attach(MIMEText(body, 'html'))

    # Add attachment
    with open(file_path, '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= {os.path.basename(file_path)}'
    )
    msg.attach(part)

    with smtplib.SMTP(SMTP_HOST, SMTP_PORT) as server:
        server.starttls()
        server.login(USERNAME, API_TOKEN)
        server.send_message(msg)

​
Lettermint Headers

Add Lettermint-specific headers for tags, metadata, and routing: 
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart

msg = MIMEMultipart('alternative')
msg['From'] = 'sender@yourdomain.com'
msg['To'] = 'recipient@example.com'
msg['Subject'] = 'Order Confirmation'

# Tag for categorization
msg['X-LM-Tag'] = 'order-confirmation'

# Metadata for tracking (included in webhooks)
msg['X-LM-Metadata-order_id'] = '12345'
msg['X-LM-Metadata-customer_id'] = 'cust_789'

# Route selection
msg['X-Lettermint-Route'] = 'transactional'

msg.attach(MIMEText('<p>Your order has been confirmed.</p>', 'html'))
Metadata headers are extracted by Lettermint and included in webhook payloads, but not added to the actual email sent to recipients. See the SMTP Introduction for full details on available headers.