Review code 100X faster

diff --git a/app/api/broadcasts/queue/route.ts b/app/api/broadcasts/queue/route.ts
index 7c31ab4..e90f118 100644
--- a/app/api/broadcasts/queue/route.ts
+++ b/app/api/broadcasts/queue/route.ts
@@ -1,8 +1,8 @@
 import { NextResponse } from "next/server";
-import { recipientsFor } from "@/lib/audience";
+import { chunk } from "@coldtea/broadcast-lib";
 import { firestore } from "@/lib/firestore";
 
 export async function POST(request: Request) {
@@ -14,26 +14,20 @@ export async function POST(request: Request) {
   const broadcast = await request.json();
 
-  const recipients = await recipientsFor(broadcast.audienceId);
-
-  for (const recipient of recipients) {
-    await firestore.collection("broadcastQueue").add({
-      broadcastId: broadcast.id,
-      email: recipient.email,
-      status: "pending",
-    });
-  }
+  await firestore.collection("broadcastQueue").add({
+    broadcastId: broadcast.id,
+    audienceId: broadcast.audienceId,
+    batchSize: chunk.MAX_PER_CALL,
+    status: "pending",
+  });
 
   return NextResponse.json({ queued: true });
 }
diff --git a/packages/broadcast-lib/index.ts b/packages/broadcast-lib/index.ts
new file mode 100644
--- /dev/null
+++ b/packages/broadcast-lib/index.ts
@@ -0,0 +1,18 @@
+export const chunk = {
+  MAX_PER_CALL: 500,
+  into<T>(items: readonly T[], size = chunk.MAX_PER_CALL): T[][] {
+    const batches: T[][] = [];
+    for (let i = 0; i < items.length; i += size) batches.push(items.slice(i, i + size));
+    return batches;
+  },
+};
diff --git a/functions/send-broadcast-bulk.ts b/functions/send-broadcast-bulk.ts
new file mode 100644
--- /dev/null
+++ b/functions/send-broadcast-bulk.ts
@@ -0,0 +1,34 @@
+import { chunk } from "@coldtea/broadcast-lib";
+import { buildBulkPayload } from "./build-bulk-payload";
+import { getSuppressedEmails } from "./get-suppressed-emails";
+
+export const sendBroadcastBulk = onWrite("broadcastQueue/{id}", async (event) => {
+  const suppressed = await getSuppressedEmails();
+  const batches = chunk.into(await audienceFor(event), chunk.MAX_PER_CALL);
+
+  for (const batch of batches) {
+    const payload = buildBulkPayload(batch, suppressed);
+    const results = await postmark.post("/email/batch", payload);
+    await writeResults(event.id, results);
+  }
+});
diff --git a/functions/process-broadcast.ts b/functions/process-broadcast.ts
deleted file mode 100644
--- a/functions/process-broadcast.ts
+++ /dev/null
@@ -1,29 +0,0 @@
-import { sendSingleEmail } from "./send-single-email";
-
-export const processBroadcast = onWrite("broadcastQueue/{id}", async (event) => {
-  const job = event.data();
-  if (job.status !== "pending") return;
-
-  await sendSingleEmail(job.email, job.broadcastId);
-  await event.ref.update({ status: "sent" });
-});
diff --git a/functions/send-single-email.ts b/functions/send-single-email.ts
deleted file mode 100644
--- a/functions/send-single-email.ts
+++ /dev/null
@@ -1,21 +0,0 @@
-export async function sendSingleEmail(to: string, broadcastId: string) {
-  return postmark.post("/email", {
-    To: to,
-    TemplateAlias: broadcastId,
-  });
-}