diff --git a/packages/sds/src/message_channel/message_channel.spec.ts b/packages/sds/src/message_channel/message_channel.spec.ts
index 6098f4c5b7..98e963a9bc 100644
--- a/packages/sds/src/message_channel/message_channel.spec.ts
+++ b/packages/sds/src/message_channel/message_channel.spec.ts
@@ -1089,13 +1089,36 @@ describe("MessageChannel", function () {
         causalHistorySize: 2
       });
       channelB = new MessageChannel(channelId, "bob", { causalHistorySize: 2 });
+      const message = utf8ToBytes("first message in channel");
+      channelA["localHistory"].push(
+        new ContentMessage(
+          MessageChannel.getMessageId(message),
+          "MyChannel",
+          "alice",
+          [],
+          1n,
+          undefined,
+          message
+        )
+      );
     });
 
     it("should be sent with empty content", async () => {
-      await channelA.pushOutgoingSyncMessage(async (message) => {
+      const res = await channelA.pushOutgoingSyncMessage(async (message) => {
         expect(message.content).to.be.undefined;
         return true;
       });
+      expect(res).to.be.true;
+    });
+
+    it("should not be sent when there is no history", async () => {
+      const channelC = new MessageChannel(channelId, "carol", {
+        causalHistorySize: 2
+      });
+      const res = await channelC.pushOutgoingSyncMessage(async (_msg) => {
+        throw "callback was called when it's not expected";
+      });
+      expect(res).to.be.false;
     });
 
     it("should not be added to outgoing buffer, bloom filter, or local log", async () => {
@@ -1110,15 +1133,16 @@ describe("MessageChannel", function () {
       ).to.equal(false);
 
       const localLog = channelA["localHistory"];
-      expect(localLog.length).to.equal(0);
+      expect(localLog.length).to.equal(1); // beforeEach adds one message
     });
 
     it("should not be delivered", async () => {
       const timestampBefore = channelB["lamportTimestamp"];
-      await channelA.pushOutgoingSyncMessage(async (message) => {
+      const res = await channelA.pushOutgoingSyncMessage(async (message) => {
         await receiveMessage(channelB, message);
         return true;
       });
+      expect(res).to.be.true;
       const timestampAfter = channelB["lamportTimestamp"];
       expect(timestampAfter).to.equal(timestampBefore);
 
@@ -1132,20 +1156,23 @@ describe("MessageChannel", function () {
     });
 
     it("should update ack status of messages in outgoing buffer", async () => {
+      const channelC = new MessageChannel(channelId, "carol", {
+        causalHistorySize: 2
+      });
       for (const m of messagesA) {
-        await sendMessage(channelA, utf8ToBytes(m), async (message) => {
+        await sendMessage(channelC, utf8ToBytes(m), async (message) => {
           await receiveMessage(channelB, message);
           return { success: true };
         });
       }
 
       await sendSyncMessage(channelB, async (message) => {
-        await receiveMessage(channelA, message);
+        await receiveMessage(channelC, message);
         return true;
       });
 
-      const causalHistorySize = channelA["causalHistorySize"];
-      const outgoingBuffer = channelA["outgoingBuffer"] as Message[];
+      const causalHistorySize = channelC["causalHistorySize"];
+      const outgoingBuffer = channelC["outgoingBuffer"] as Message[];
       expect(outgoingBuffer.length).to.equal(
         messagesA.length - causalHistorySize
       );
diff --git a/packages/sds/src/message_channel/message_channel.ts b/packages/sds/src/message_channel/message_channel.ts
index 37dd1a6160..f81f8bad20 100644
--- a/packages/sds/src/message_channel/message_channel.ts
+++ b/packages/sds/src/message_channel/message_channel.ts
@@ -384,6 +384,14 @@ export class MessageChannel extends TypedEventEmitter<MessageChannelEvents> {
       undefined
     );
 
+    if (!message.causalHistory || message.causalHistory.length === 0) {
+      log.info(
+        this.senderId,
+        "no causal history in sync message, aborting sending"
+      );
+      return false;
+    }
+
     if (callback) {
       try {
         await callback(message);
@@ -400,6 +408,7 @@ export class MessageChannel extends TypedEventEmitter<MessageChannelEvents> {
         throw error;
       }
     }
+    // Why returning false if no callback is set?
     return false;
   }