diff --git a/appview/index.ts b/appview/index.ts
--- a/appview/index.ts
+++ b/appview/index.ts
@@ -118,6 +118,7 @@
         data: {
           document_uri: evt.uri.toString(),
           bsky_post_uri: record.value.postRef?.uri,
+          event_type: evt.event,
         },
       });
       if (record.value.publication) {
@@ -285,6 +286,7 @@
         data: {
           document_uri: evt.uri.toString(),
           bsky_post_uri: record.value.bskyPostRef?.uri,
+          event_type: evt.event,
         },
       });
 
diff --git a/app/api/inngest/client.ts b/app/api/inngest/client.ts
--- a/app/api/inngest/client.ts
+++ b/app/api/inngest/client.ts
@@ -42,7 +42,11 @@
     schema: staticSchema<{ documentUris?: string[] }>(),
   }),
   appviewSyncDocumentMetadata: eventType("appview/sync-document-metadata", {
-    schema: staticSchema<{ document_uri: string; bsky_post_uri?: string }>(),
+    schema: staticSchema<{
+      document_uri: string;
+      bsky_post_uri?: string;
+      event_type?: "create" | "update";
+    }>(),
   }),
   userWriteRecordsToPds: eventType("user/write-records-to-pds", {
     schema: staticSchema<{
diff --git a/app/api/inngest/functions/sync_document_metadata.ts b/app/api/inngest/functions/sync_document_metadata.ts
--- a/app/api/inngest/functions/sync_document_metadata.ts
+++ b/app/api/inngest/functions/sync_document_metadata.ts
@@ -20,7 +20,7 @@
     triggers: [events.appviewSyncDocumentMetadata],
   },
   async ({ event, step }) => {
-    const { document_uri, bsky_post_uri } = event.data;
+    const { document_uri, bsky_post_uri, event_type } = event.data;
 
     const did = new AtUri(document_uri).host;
 
@@ -57,55 +57,58 @@
         .select();
     });
 
-    const broadcast = await step.run(
-      "maybe-claim-newsletter-broadcast",
-      async () => {
-        const { data: docInPub } = await supabaseServerClient
-          .from("documents_in_publications")
-          .select("publication")
-          .eq("document", document_uri)
-          .maybeSingle();
-        const publication_uri = docInPub?.publication;
-        if (!publication_uri) return { skipped: "no_publication" as const };
+    // Only fire newsletter broadcasts on first-time document creation. An
+    // update to an existing post must never trigger a send — otherwise editing
+    // an old post after newsletters were enabled would mail subscribers a post
+    // they never signed up for.
+    if (event_type === "create") {
+      const broadcast = await step.run(
+        "maybe-claim-newsletter-broadcast",
+        async () => {
+          const { data: docInPub } = await supabaseServerClient
+            .from("documents_in_publications")
+            .select("publication")
+            .eq("document", document_uri)
+            .maybeSingle();
+          const publication_uri = docInPub?.publication;
+          if (!publication_uri) return { skipped: "no_publication" as const };
 
-        const { data: settings } = await supabaseServerClient
-          .from("publication_newsletter_settings")
-          .select("enabled")
-          .eq("publication", publication_uri)
-          .maybeSingle();
-        if (!settings?.enabled) {
-          return { skipped: "newsletter_not_enabled" as const };
-        }
+          const { data: settings } = await supabaseServerClient
+            .from("publication_newsletter_settings")
+            .select("enabled")
+            .eq("publication", publication_uri)
+            .maybeSingle();
+          if (!settings?.enabled) {
+            return { skipped: "newsletter_not_enabled" as const };
+          }
 
-        // Composite PK on (publication, document) is the idempotency guard:
-        // re-runs on document updates and races with publishToPublication
-        // both no-op here.
-        const { data: inserted } = await supabaseServerClient
-          .from("publication_post_sends")
-          .upsert(
-            {
-              publication: publication_uri,
-              document: document_uri,
-              status: "pending",
-            },
-            { onConflict: "publication,document", ignoreDuplicates: true },
-          )
-          .select();
-        if (!inserted || inserted.length === 0) {
-          return { skipped: "already_sent_or_pending" as const };
-        }
-        return { claimed: true as const, publication_uri };
-      },
-    );
-
-    if ("claimed" in broadcast) {
-      await step.sendEvent("send-newsletter-broadcast", {
-        name: "newsletter/post.send.requested",
-        data: {
-          publication_uri: broadcast.publication_uri,
-          document_uri,
+          const { data: inserted } = await supabaseServerClient
+            .from("publication_post_sends")
+            .upsert(
+              {
+                publication: publication_uri,
+                document: document_uri,
+                status: "pending",
+              },
+              { onConflict: "publication,document", ignoreDuplicates: true },
+            )
+            .select();
+          if (!inserted || inserted.length === 0) {
+            return { skipped: "already_sent_or_pending" as const };
+          }
+          return { claimed: true as const, publication_uri };
         },
-      });
+      );
+
+      if ("claimed" in broadcast) {
+        await step.sendEvent("send-newsletter-broadcast", {
+          name: "newsletter/post.send.requested",
+          data: {
+            publication_uri: broadcast.publication_uri,
+            document_uri,
+          },
+        });
+      }
     }
 
     if (!bsky_post_uri) {