Invoice emails with the PDF attached, within the limits.

# Your app renders the PDF. Notix carries it. The attachment is base64
# in the request body, and the idempotency key names the invoice so a
# retry cannot send it twice.
PDF_B64=$(base64 < invoice-2026-0912.pdf | tr -d '\n')

curl -X POST https://app.usenotix.dev/api/v1/emails \
  -H "Authorization: Bearer $NOTIX_API_KEY" \
  -H "Idempotency-Key: invoice-2026-0912-send" \
  -H "Content-Type: application/json" \
  -d "{
    \"from\": \"Acme Billing <billing@acme.com>\",
    \"to\": \"accounts@example.com\",
    \"replyTo\": \"billing@acme.com\",
    \"subject\": \"Invoice 2026-0912 from Acme, due 26 September\",
    \"templateId\": \"tpl_invoice\",
    \"variables\": {
      \"invoiceNumber\": \"2026-0912\",
      \"amountDue\": \"NGN 412,500\",
      \"dueDate\": \"26 September 2026\",
      \"payUrl\": \"https://acme.com/pay/2026-0912\"
    },
    \"attachments\": [
      { \"filename\": \"invoice-2026-0912.pdf\", \"content\": \"$PDF_B64\" }
    ]
  }"

# 200 { "emailId": "eml_abc123" }
# Too big: 400 with the field and the limit, e.g.
# { "path": ["attachments", 0, "content"], "message": "Attachment content must be at most 7 MB once decoded." }

import { Notix } from "notix-js";

const notix = new Notix(process.env.NOTIX_API_KEY);
const SEVEN_MB = 7 * 1024 * 1024;

export async function sendInvoice(invoiceId: string) {
  const invoice = await db.invoice.findUniqueOrThrow({ where: { id: invoiceId }, include: { customer: true } });

  // Your renderer, your PDF. Notix does not generate documents.
  const pdf: Buffer = await renderInvoicePdf(invoice);

  // Over the per-file limit? Send a link instead of the file (see below).
  const attachments =
    pdf.byteLength <= SEVEN_MB
      ? [{ filename: `invoice-${invoice.number}.pdf`, content: pdf.toString("base64") }]
      : undefined;

  const { data, error } = await notix.emails.send(
    {
      from: "Acme Billing <billing@acme.com>",
      to: invoice.customer.billingEmail,
      replyTo: "billing@acme.com",
      subject: `Invoice ${invoice.number} from Acme, due ${formatDate(invoice.dueDate)}`,
      templateId: "tpl_invoice",
      variables: {
        invoiceNumber: invoice.number,
        amountDue: formatMoney(invoice.totalMinor, invoice.currency),
        dueDate: formatDate(invoice.dueDate),
        payUrl: `https://acme.com/pay/${invoice.number}`,
        // The template shows this link when the PDF was too big to attach.
        downloadUrl: attachments ? "" : `https://acme.com/invoices/${invoice.number}.pdf`,
      },
      attachments,
      // Optional: send on the invoice date rather than now. ISO 8601 with an offset.
      scheduledAt: invoice.issueAt.toISOString(),
    },
    { idempotencyKey: `invoice-${invoice.id}-send` },
  );

  if (error) throw new Error(`invoice email failed: ${error.code} ${error.message}`);
  await db.invoice.update({ where: { id: invoice.id }, data: { emailId: data.emailId } });
}

import base64
import os

from notix import Notix

notix = Notix(os.environ["NOTIX_API_KEY"])
SEVEN_MB = 7 * 1024 * 1024


def send_invoice(invoice_id: str) -> None:
    invoice = db.invoices.get(invoice_id, include=["customer"])

    # Your renderer, your PDF. Notix does not generate documents.
    pdf: bytes = render_invoice_pdf(invoice)

    # Over the per-file limit? Send a link instead of the file (see below).
    attachments = (
        [{"filename": f"invoice-{invoice.number}.pdf", "content": base64.b64encode(pdf).decode()}]
        if len(pdf) <= SEVEN_MB
        else None
    )

    payload = {
        "from": "Acme Billing <billing@acme.com>",
        "to": invoice.customer.billing_email,
        "replyTo": "billing@acme.com",
        "subject": f"Invoice {invoice.number} from Acme, due {format_date(invoice.due_date)}",
        "templateId": "tpl_invoice",
        "variables": {
            "invoiceNumber": invoice.number,
            "amountDue": format_money(invoice.total_minor, invoice.currency),
            "dueDate": format_date(invoice.due_date),
            "payUrl": f"https://acme.com/pay/{invoice.number}",
            # The template shows this link when the PDF was too big to attach.
            "downloadUrl": "" if attachments else f"https://acme.com/invoices/{invoice.number}.pdf",
        },
        # Optional: send on the invoice date rather than now. ISO 8601 with an offset.
        "scheduledAt": invoice.issue_at.isoformat(),
    }
    if attachments:
        payload["attachments"] = attachments

    data, error = notix.emails.send(
        payload=payload,
        options={"idempotency_key": f"invoice-{invoice.id}-send"},
    )
    if error:
        raise RuntimeError(f"invoice email failed: {error['code']} {error['message']}")
    db.invoices.update(invoice.id, email_id=data["emailId"])