diff --git a/spec/integ/matrix-client-methods.spec.ts b/spec/integ/matrix-client-methods.spec.ts
index c1c4c30dc..01e24ded4 100644
--- a/spec/integ/matrix-client-methods.spec.ts
+++ b/spec/integ/matrix-client-methods.spec.ts
@@ -1177,11 +1177,10 @@ describe("MatrixClient", function () {
                 .when("PUT", "/send")
                 .check((req) => {
                     expect(req.data).toStrictEqual({
-                        "msgtype": "m.emote",
-                        "body": "Body",
-                        "formatted_body": "<h1>Body</h1>",
-                        "format": "org.matrix.custom.html",
-                        "org.matrix.msc1767.message": expect.anything(),
+                        msgtype: "m.emote",
+                        body: "Body",
+                        formatted_body: "<h1>Body</h1>",
+                        format: "org.matrix.custom.html",
                     });
                 })
                 .respond(200, { event_id: "$foobar" });
@@ -1197,11 +1196,10 @@ describe("MatrixClient", function () {
                 .when("PUT", "/send")
                 .check((req) => {
                     expect(req.data).toStrictEqual({
-                        "msgtype": "m.text",
-                        "body": "Body",
-                        "formatted_body": "<h1>Body</h1>",
-                        "format": "org.matrix.custom.html",
-                        "org.matrix.msc1767.message": expect.anything(),
+                        msgtype: "m.text",
+                        body: "Body",
+                        formatted_body: "<h1>Body</h1>",
+                        format: "org.matrix.custom.html",
                     });
                 })
                 .respond(200, { event_id: "$foobar" });
diff --git a/src/client.ts b/src/client.ts
index 551119307..c7c75b35d 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -18,7 +18,7 @@ limitations under the License.
  * This is an internal module. See {@link MatrixClient} for the public class.
  */
 
-import { EmoteEvent, IPartialEvent, MessageEvent, NoticeEvent, Optional } from "matrix-events-sdk";
+import { Optional } from "matrix-events-sdk";
 
 import type { IMegolmSessionData } from "./@types/crypto";
 import { ISyncStateData, SyncApi, SyncApiOptions, SyncState } from "./sync";
@@ -4541,44 +4541,8 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
             threadId = null;
         }
 
-        // Populate all outbound events with Extensible Events metadata to ensure there's a
-        // reasonably large pool of messages to parse.
-        let eventType: string = EventType.RoomMessage;
-        let sendContent: IContent = content as IContent;
-        const makeContentExtensible = (content: IContent = {}, recurse = true): IPartialEvent<object> | undefined => {
-            let newEvent: IPartialEvent<IContent> | undefined;
-
-            if (content["msgtype"] === MsgType.Text) {
-                newEvent = MessageEvent.from(content["body"], content["formatted_body"]).serialize();
-            } else if (content["msgtype"] === MsgType.Emote) {
-                newEvent = EmoteEvent.from(content["body"], content["formatted_body"]).serialize();
-            } else if (content["msgtype"] === MsgType.Notice) {
-                newEvent = NoticeEvent.from(content["body"], content["formatted_body"]).serialize();
-            }
-
-            if (newEvent && content["m.new_content"] && recurse) {
-                const newContent = makeContentExtensible(content["m.new_content"], false);
-                if (newContent) {
-                    newEvent.content["m.new_content"] = newContent.content;
-                }
-            }
-
-            if (newEvent) {
-                // copy over all other fields we don't know about
-                for (const [k, v] of Object.entries(content)) {
-                    if (!newEvent.content.hasOwnProperty(k)) {
-                        newEvent.content[k] = v;
-                    }
-                }
-            }
-
-            return newEvent;
-        };
-        const result = makeContentExtensible(sendContent);
-        if (result) {
-            eventType = result.type;
-            sendContent = result.content;
-        }
+        const eventType: string = EventType.RoomMessage;
+        const sendContent: IContent = content as IContent;
 
         return this.sendEvent(roomId, threadId as string | null, eventType, sendContent, txnId);
     }