diff --git a/src/BridgedRoom.ts b/src/BridgedRoom.ts
index 126d6815..59d8ec5b 100644
--- a/src/BridgedRoom.ts
+++ b/src/BridgedRoom.ts
@@ -159,11 +159,17 @@ export class BridgedRoom {
     public MatrixRoomActive: boolean;
     private recentSlackMessages: string[] = [];
 
-    private slackSendLock: Promise<unknown> = Promise.resolve();
+    private bridgingQueue: Promise<unknown> = Promise.resolve();
 
     private waitingForJoin?: Promise<void>;
     private waitingForJoinResolve?: () => void;
 
+    private async pushToBridgingQueue<T>(fn: () => Promise<T>): Promise<T> {
+        return new Promise((resolve) => {
+            this.bridgingQueue = this.bridgingQueue.finally(() => fn().then(resolve));
+        });
+    }
+
     /**
      * True if this instance has changed from the version last read/written to the RoomStore.
      */
@@ -528,7 +534,6 @@ export class BridgedRoom {
             body.as_user = true;
             delete body.username;
         }
-        let res: ChatPostMessageResponse;
         const chatPostMessageArgs = {
             ...body,
             // Ensure that text is defined, even for attachments.
@@ -537,21 +542,25 @@ export class BridgedRoom {
             unfurl_links: true,
         };
 
-        try {
-            res = await slackClient.chat.postMessage(chatPostMessageArgs) as ChatPostMessageResponse;
-        } catch (ex) {
-            const platformError = ex as WebAPIPlatformError;
-            if (platformError.data?.error === "not_in_channel") {
-                await slackClient.conversations.join({
-                    channel: chatPostMessageArgs.channel,
-                });
+        const res = await this.pushToBridgingQueue(async () => {
+            let res: ChatPostMessageResponse;
+            try {
                 res = await slackClient.chat.postMessage(chatPostMessageArgs) as ChatPostMessageResponse;
-            } else {
-                throw ex;
+            } catch (ex) {
+                const platformError = ex as WebAPIPlatformError;
+                if (platformError.data?.error === "not_in_channel") {
+                    await slackClient.conversations.join({
+                        channel: chatPostMessageArgs.channel,
+                    });
+                    res = await slackClient.chat.postMessage(chatPostMessageArgs) as ChatPostMessageResponse;
+                } else {
+                    throw ex;
+                }
             }
-        }
 
-        this.addRecentSlackMessage(res.ts);
+            this.addRecentSlackMessage(res.ts);
+            return res;
+        });
 
         this.main.incCounter(METRIC_SENT_MESSAGES, {side: "remote"});
         // Log activity, but don't await the answer or throw errors
@@ -710,7 +719,7 @@ export class BridgedRoom {
             if (ghostChanged) {
                 await this.main.fixDMMetadata(this, ghost);
             }
-            this.slackSendLock = this.slackSendLock.then(() => {
+            await this.pushToBridgingQueue(async () => {
                 // Check again
                 if (this.recentSlackMessages.includes(message.ts)) {
                     // We sent this, ignore
@@ -720,7 +729,6 @@ export class BridgedRoom {
                     log.warn(`Failed to handle slack message ${message.ts} for ${this.MatrixRoomId} ${this.slackChannelId}`, ex);
                 });
             });
-            await this.slackSendLock;
         } catch (err) {
             log.error("Failed to process event");
             log.error(err);