diff --git a/CHANGES.md b/CHANGES.md
index 51e4d299..e8cbdcbf 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -34,6 +34,9 @@ To be released.
  -  `Context.sendActivity()` method now throws `TypeError` instead of silently
     failing when the given `Activity` object lacks the actor property.
 
+ -  `Context.sendActivity()` method now uses an authenticated document
+    loader under the hood.
+
  -  Added outbox error handler to `Federation`.
 
      -  Added `onOutboxError` option to `new Federation()` constructor.
diff --git a/federation/middleware.ts b/federation/middleware.ts
index 2105b74b..24b252cd 100644
--- a/federation/middleware.ts
+++ b/federation/middleware.ts
@@ -198,15 +198,20 @@ export class Federation<TContextData> {
   async #listenQueue(message: OutboxMessage): Promise<void> {
     let activity: Activity | null = null;
     try {
+      const keyId = new URL(message.keyId);
+      const privateKey = await importJwk(message.privateKey, "private");
+      const documentLoader = this.#authenticatedDocumentLoaderFactory(
+        { keyId, privateKey },
+      );
       activity = await Activity.fromJsonLd(message.activity, {
-        documentLoader: this.#documentLoader,
+        documentLoader,
       });
       await sendActivity({
-        keyId: new URL(message.keyId),
-        privateKey: await importJwk(message.privateKey, "private"),
+        keyId,
+        privateKey,
         activity,
         inbox: new URL(message.inbox),
-        documentLoader: this.#documentLoader,
+        documentLoader,
       });
     } catch (e) {
       try {
@@ -721,6 +726,9 @@ export class Federation<TContextData> {
       preferSharedInbox,
     });
     if (immediate || this.#queue == null) {
+      const documentLoader = this.#authenticatedDocumentLoaderFactory(
+        { keyId, privateKey },
+      );
       const promises: Promise<void>[] = [];
       for (const inbox of inboxes) {
         promises.push(
@@ -729,7 +737,7 @@ export class Federation<TContextData> {
             privateKey,
             activity,
             inbox,
-            documentLoader: this.#documentLoader,
+            documentLoader,
           }),
         );
       }