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SMTP

Python (smtplib)

Use Python's smtplib module to send email through the Lettermint SMTP relay.

Basic configuration

Use environment variables for credentials:

Code
import os

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

Advanced features

Multiple recipients

Code
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

Code
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:

Code
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'

# Existing singular tag
msg['X-LM-Tag'] = 'order-confirmation'

# Structured tags. MIMEMultipart permits repeated custom headers.
msg['X-LM-Tags'] = 'campaign=orders, environment=production'
msg['X-LM-Tags'] = 'variant=B'

# 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'))

X-LM-Tag is the singular tag. X-LM-Tags contains structured pairs. Assign the custom field again to add another header.