diff --git a/extensions/msteams/src/monitor-handler/message-handler.ts b/extensions/msteams/src/monitor-handler/message-handler.ts
index e3ad16f5781..48d8289b5a3 100644
--- a/extensions/msteams/src/monitor-handler/message-handler.ts
+++ b/extensions/msteams/src/monitor-handler/message-handler.ts
@@ -620,6 +620,7 @@ export function createMSTeamsMessageHandler(deps: MSTeamsMessageHandlerDeps) {
     const { dispatcher, replyOptions, markDispatchIdle } = createMSTeamsReplyDispatcher({
       cfg,
       agentId: route.agentId,
+      sessionKey: route.sessionKey,
       accountId: route.accountId,
       runtime,
       log,
diff --git a/extensions/msteams/src/reply-dispatcher.test.ts b/extensions/msteams/src/reply-dispatcher.test.ts
index b2fda18f487..09a5072fbed 100644
--- a/extensions/msteams/src/reply-dispatcher.test.ts
+++ b/extensions/msteams/src/reply-dispatcher.test.ts
@@ -3,6 +3,7 @@ import { beforeEach, describe, expect, it, vi } from "vitest";
 const createChannelReplyPipelineMock = vi.hoisted(() => vi.fn());
 const createReplyDispatcherWithTypingMock = vi.hoisted(() => vi.fn());
 const getMSTeamsRuntimeMock = vi.hoisted(() => vi.fn());
+const enqueueSystemEventMock = vi.hoisted(() => vi.fn());
 const renderReplyPayloadsToMessagesMock = vi.hoisted(() => vi.fn(() => []));
 const sendMSTeamsMessagesMock = vi.hoisted(() => vi.fn(async () => []));
 const streamInstances = vi.hoisted(
@@ -86,6 +87,9 @@ describe("createMSTeamsReplyDispatcher", () => {
     }));
 
     getMSTeamsRuntimeMock.mockReturnValue({
+      system: {
+        enqueueSystemEvent: enqueueSystemEventMock,
+      },
       channel: {
         text: {
           resolveChunkMode: vi.fn(() => "length"),
@@ -102,10 +106,12 @@ describe("createMSTeamsReplyDispatcher", () => {
   function createDispatcher(
     conversationType: string = "personal",
     msteamsConfig: Record<string, unknown> = {},
+    extraParams: { onSentMessageIds?: (ids: string[]) => void } = {},
   ) {
     return createMSTeamsReplyDispatcher({
       cfg: { channels: { msteams: msteamsConfig } } as never,
       agentId: "agent",
+      sessionKey: "agent:main:main",
       runtime: { error: vi.fn() } as never,
       log: { debug: vi.fn(), error: vi.fn(), warn: vi.fn() } as never,
       adapter: {
@@ -127,6 +133,7 @@ describe("createMSTeamsReplyDispatcher", () => {
       } as never,
       replyStyle: "thread",
       textLimit: 4000,
+      ...extraParams,
     });
   }
 
@@ -206,6 +213,54 @@ describe("createMSTeamsReplyDispatcher", () => {
 
     expect(sendMSTeamsMessagesMock).not.toHaveBeenCalled();
   });
+
+  it("queues a system event when some queued Teams messages fail to send", async () => {
+    const onSentMessageIds = vi.fn();
+    renderReplyPayloadsToMessagesMock.mockReturnValue([
+      { content: "one" },
+      { content: "two" },
+    ] as never);
+    sendMSTeamsMessagesMock
+      .mockRejectedValueOnce(Object.assign(new Error("gateway timeout"), { statusCode: 502 }))
+      .mockResolvedValueOnce(["id-1"] as never)
+      .mockRejectedValueOnce(Object.assign(new Error("gateway timeout"), { statusCode: 502 }));
+
+    const dispatcher = createDispatcher(
+      "personal",
+      { blockStreaming: false },
+      { onSentMessageIds },
+    );
+    const options = createReplyDispatcherWithTypingMock.mock.calls[0]?.[0];
+
+    await options.deliver({ text: "block content" });
+    await dispatcher.markDispatchIdle();
+
+    expect(onSentMessageIds).toHaveBeenCalledWith(["id-1"]);
+    expect(enqueueSystemEventMock).toHaveBeenCalledWith(
+      expect.stringContaining("Microsoft Teams delivery failed"),
+      expect.objectContaining({
+        sessionKey: "agent:main:main",
+        contextKey: "msteams:delivery-failure:conv",
+      }),
+    );
+    expect(enqueueSystemEventMock).toHaveBeenCalledWith(
+      expect.stringContaining("The user may not have received the full reply"),
+      expect.any(Object),
+    );
+  });
+
+  it("does not queue a delivery-failure system event when Teams send succeeds", async () => {
+    renderReplyPayloadsToMessagesMock.mockReturnValue([{ content: "hello" }] as never);
+    sendMSTeamsMessagesMock.mockResolvedValue(["id-1"] as never);
+
+    const dispatcher = createDispatcher("personal", { blockStreaming: false });
+    const options = createReplyDispatcherWithTypingMock.mock.calls[0]?.[0];
+
+    await options.deliver({ text: "block content" });
+    await dispatcher.markDispatchIdle();
+
+    expect(enqueueSystemEventMock).not.toHaveBeenCalled();
+  });
 });
 
 describe("pickInformativeStatusText", () => {
diff --git a/extensions/msteams/src/reply-dispatcher.ts b/extensions/msteams/src/reply-dispatcher.ts
index bfcd1740d41..f235b6c0958 100644
--- a/extensions/msteams/src/reply-dispatcher.ts
+++ b/extensions/msteams/src/reply-dispatcher.ts
@@ -31,6 +31,7 @@ export { pickInformativeStatusText } from "./reply-stream-controller.js";
 export function createMSTeamsReplyDispatcher(params: {
   cfg: OpenClawConfig;
   agentId: string;
+  sessionKey: string;
   accountId?: string;
   runtime: RuntimeEnv;
   log: MSTeamsMonitorLogger;
@@ -134,6 +135,32 @@ export function createMSTeamsReplyDispatcher(params: {
     });
   };
 
+  const queueDeliveryFailureSystemEvent = (failure: {
+    failed: number;
+    total: number;
+    error: unknown;
+  }) => {
+    const classification = classifyMSTeamsSendError(failure.error);
+    const errorText = formatUnknownError(failure.error);
+    const failedAll = failure.failed >= failure.total;
+    const summary = failedAll
+      ? "the previous reply was not delivered"
+      : `${failure.failed} of ${failure.total} message blocks were not delivered`;
+    const sentences = [
+      `Microsoft Teams delivery failed: ${summary}.`,
+      `The user may not have received ${failedAll ? "that reply" : "the full reply"}.`,
+      `Error: ${errorText}.`,
+      classification.statusCode != null ? `Status: ${classification.statusCode}.` : undefined,
+      classification.kind === "transient" || classification.kind === "throttled"
+        ? "Retrying later may succeed."
+        : undefined,
+    ].filter(Boolean);
+    core.system.enqueueSystemEvent(sentences.join(" "), {
+      sessionKey: params.sessionKey,
+      contextKey: `msteams:delivery-failure:${params.conversationRef.conversation?.id ?? "unknown"}`,
+    });
+  };
+
   const flushPendingMessages = async () => {
     if (pendingMessages.length === 0) {
       return;
@@ -143,15 +170,17 @@ export function createMSTeamsReplyDispatcher(params: {
     let ids: string[];
     try {
       ids = await sendMessages(toSend);
-    } catch {
+    } catch (batchError) {
       ids = [];
       let failed = 0;
+      let lastFailedError: unknown = batchError;
       for (const msg of toSend) {
         try {
           const msgIds = await sendMessages([msg]);
           ids.push(...msgIds);
-        } catch {
+        } catch (msgError) {
           failed += 1;
+          lastFailedError = msgError;
           params.log.debug?.("individual message send failed, continuing with remaining blocks");
         }
       }
@@ -160,6 +189,11 @@ export function createMSTeamsReplyDispatcher(params: {
           failed,
           total,
         });
+        queueDeliveryFailureSystemEvent({
+          failed,
+          total,
+          error: lastFailedError,
+        });
       }
     }
     if (ids.length > 0) {