Postscale Python SDK

Official Python SDK for the Postscale email API.

Install

pip install postscale

Send Email

import os

from postscale import Postscale

postscale = Postscale(os.environ["POSTSCALE_API_KEY"])

result = postscale.emails.send({
    "from": "hello@example.com",
    "to": ["user@example.com"],
    "subject": "Welcome to Postscale",
    "html_body": "<strong>It works.</strong>",
})

if result.error:
    raise RuntimeError(f"{result.error.code}: {result.error.message}")

print(result.data["message_id"])

The SDK keeps Postscale API-native field names. Use html_body, text_body, template_id, and unsubscribe_scope; the MVP SDK does not add html or text aliases.

Attachments

from postscale import Postscale, attachment_from_file

postscale = Postscale()

result = postscale.emails.send({
    "from": "hello@example.com",
    "to": ["user@example.com"],
    "subject": "Invoice",
    "text_body": "Attached.",
    "attachments": [
        attachment_from_file("invoice.pdf", "application/pdf"),
    ],
})

Attachment helpers enforce the documented limits before sending: 10 attachments, 25 MB per attachment, and 50 MB total decoded attachment payload.

Webhook Verification

from postscale import verify_webhook_signature

verified = verify_webhook_signature(
    raw_body,
    request.headers.get("X-Postscale-Signature"),
    [current_secret, previous_secret],
)

if not verified.valid:
    return "invalid", 401

The verifier requires the Postscale signature format: t=<unix_seconds>,v1=<hex_hmac_sha256>, signed over <t>.<raw_body>. It supports multiple v1= signatures and multiple candidate secrets for rotation windows.