Send emails with Django

# settings.py — read the key from the environment, never hardcode it
import os

POSTSTACK_API_KEY = os.environ["POSTSTACK_API_KEY"]

# emails.py — a thin service module your views and tasks import
from poststack import PostStack
from django.conf import settings

ps = PostStack(api_key=settings.POSTSTACK_API_KEY)

# emails.py
from django.conf import settings
from poststack import PostStack, PostStackError

ps = PostStack(api_key=settings.POSTSTACK_API_KEY)

def send_welcome_email(user):
    return ps.emails.send({
        "from": "hello@yourdomain.com",
        "to": [user.email],
        "subject": "Welcome to Acme",
        "html": f"<h1>Welcome, {user.get_short_name()}!</h1>",
    })

# views.py — dispatch to Celery so the request returns immediately
from django.http import JsonResponse
from .tasks import send_welcome_email_task

def signup(request):
    user = create_user(request.POST)
    send_welcome_email_task.delay(user.id)  # non-blocking
    return JsonResponse({"ok": True})

# tasks.py
from celery import shared_task
from django.contrib.auth import get_user_model
from .emails import send_welcome_email

@shared_task(bind=True, max_retries=3)
def send_welcome_email_task(self, user_id):
    user = get_user_model().objects.get(pk=user_id)
    try:
        result = send_welcome_email(user)
        user.welcome_email_id = result["id"]  # correlate webhooks later
        user.save(update_fields=["welcome_email_id"])
    except PostStackError as exc:
        raise self.retry(exc=exc, countdown=2 ** self.request.retries)

import os
import logging
from celery import shared_task
from poststack import PostStack, PostStackError

logger = logging.getLogger(__name__)
ps = PostStack(api_key=os.environ["POSTSTACK_API_KEY"])

@shared_task(bind=True, max_retries=3)
def send_email_task(self, payload):
    try:
        return ps.emails.send(payload)
    except PostStackError as exc:
        # The SDK already retried 429/5xx internally; only re-queue on a
        # terminal server error, and never retry a 4xx (bad payload/recipient).
        if exc.status_code >= 500 or exc.status_code == 429:
            raise self.retry(exc=exc, countdown=2 ** self.request.retries)
        logger.error("PostStack %s: %s (req %s)", exc.code, exc.error, exc.request_id)
        return None

# settings.py — route Django's built-in email through PostStack over SMTP
import os

EMAIL_BACKEND = "django.core.mail.backends.smtp.EmailBackend"
EMAIL_HOST = "smtp.poststack.dev"
EMAIL_PORT = 587
EMAIL_USE_SSL = True            # implicit TLS on 587 (RFC 8314) — do NOT also set EMAIL_USE_TLS
EMAIL_HOST_USER = "poststack"
EMAIL_HOST_PASSWORD = os.environ["POSTSTACK_API_KEY"]
DEFAULT_FROM_EMAIL = "hello@yourdomain.com"

# 1. send_mail — the one-liner
from django.core.mail import send_mail

send_mail(
    "Welcome to Acme",
    "Thanks for signing up.",
    None,                       # None uses DEFAULT_FROM_EMAIL
    ["user@example.com"],
)

# 2. EmailMultiAlternatives — HTML with a plain-text fallback
from django.core.mail import EmailMultiAlternatives

msg = EmailMultiAlternatives(
    subject="Welcome",
    body="Thanks for signing up.",          # text/plain part
    to=["user@example.com"],
)
msg.attach_alternative("<h1>Welcome!</h1>", "text/html")
msg.send()

# 3. EmailMessage — attach a file (e.g. a PDF receipt)
from django.core.mail import EmailMessage

email = EmailMessage(
    subject="Your receipt",
    body="Your receipt is attached.",
    to=["user@example.com"],
)
email.attach("receipt.pdf", pdf_bytes, "application/pdf")
email.send()