How to Send Email with Python

Method 1: REST API with requests

The simplest approach. Install requests and make a single POST call.

import requests
import os

response = requests.post(
    "https://api.relaypost.dev/v1/emails/send",
    headers={
        "Content-Type": "application/json",
        "Authorization": f"Bearer {os.environ['RELAYPOST_API_KEY']}",
    },
    json={
        "from": {"email": "[email protected]", "name": "Your App"},
        "to": [{"email": "[email protected]"}],
        "subject": "Your order has shipped",
        "html": "<h1>Order Shipped</h1><p>Your package is on the way.</p>",
    },
)

result = response.json()
print(result["data"]["message_id"])

Method 2: SMTP with smtplib

Python's built-in smtplib works with any SMTP relay. No external dependencies.

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

msg = MIMEMultipart("alternative")
msg["Subject"] = "Your order has shipped"
msg["From"] = "[email protected]"
msg["To"] = "[email protected]"

html = "<h1>Order Shipped</h1><p>Your package is on the way.</p>"
msg.attach(MIMEText(html, "html"))

with smtplib.SMTP("smtp.relaypost.dev", 587) as server:
    server.starttls()
    server.login(os.environ["SMTP_USERNAME"], os.environ["SMTP_PASSWORD"])
    server.sendmail(msg["From"], [msg["To"]], msg.as_string())

Django integration

Django has built-in email support via SMTP. Add these settings to your settings.py:

# settings.py
EMAIL_BACKEND = "django.core.mail.backends.smtp.EmailBackend"
EMAIL_HOST = "smtp.relaypost.dev"
EMAIL_PORT = 587
EMAIL_USE_TLS = True
EMAIL_HOST_USER = os.environ["SMTP_USERNAME"]
EMAIL_HOST_PASSWORD = os.environ["SMTP_PASSWORD"]
DEFAULT_FROM_EMAIL = "[email protected]"

Then send email from any view or management command:

from django.core.mail import send_mail

send_mail(
    subject="Welcome to YourApp",
    message="Thanks for signing up.",
    from_email="[email protected]",
    recipient_list=["[email protected]"],
    html_message="<h1>Welcome!</h1><p>Your account is ready.</p>",
)

Flask integration

Use the requests library directly in Flask routes — no Flask-Mail needed.

from flask import Flask, request, jsonify
import requests as http
import os

app = Flask(__name__)

@app.route("/register", methods=["POST"])
def register():
    data = request.get_json()
    # ... create user in database ...

    http.post(
        "https://api.relaypost.dev/v1/emails/send",
        headers={"Authorization": f"Bearer {os.environ['RELAYPOST_API_KEY']}"},
        json={
            "from": {"email": "[email protected]"},
            "to": [{"email": data["email"]}],
            "subject": "Welcome to YourApp",
            "html": "<h1>Welcome!</h1><p>Your account is ready.</p>",
        },
    )
    return jsonify(success=True)

Error handling

import requests
import os

try:
    response = requests.post(
        "https://api.relaypost.dev/v1/emails/send",
        headers={"Authorization": f"Bearer {os.environ['RELAYPOST_API_KEY']}"},
        json={
            "from": {"email": "[email protected]"},
            "to": [{"email": "[email protected]"}],
            "subject": "Hello",
            "html": "<p>Hello from RelayPost</p>",
        },
    )
    response.raise_for_status()
    print(response.json()["data"]["message_id"])
except requests.exceptions.HTTPError as e:
    error = e.response.json()
    print(f"Send failed: {error['error']['code']} - {error['error']['message']}")
except requests.exceptions.RequestException as e:
    print(f"Network error: {e}")

Best practices

• Store API keys in environment variables, never in source code
• Set up SPF and DKIM for your sending domain before production sends
• Include both html and text content for maximum compatibility
• Use a task queue (Celery, RQ) for non-critical emails to keep request latency low
• Handle errors gracefully and retry transient failures
• Use webhooks to track delivery status instead of polling the API