diff --git a/lib/handlers/peer-to-peer-message-handler.js b/lib/handlers/peer-to-peer-message-handler.js
--- a/lib/handlers/peer-to-peer-message-handler.js
+++ b/lib/handlers/peer-to-peer-message-handler.js
@@ -13,14 +13,16 @@
 } from '../types/tunnelbroker/peer-to-peer-message-types.js';
 import { getConfig } from '../utils/config.js';
 import { getContentSigningKey } from '../utils/crypto-utils.js';
+import { getMessageForException } from '../utils/errors.js';
 import { hasHigherDeviceID, olmSessionErrors } from '../utils/olm-utils.js';
+import { getClientMessageIDFromTunnelbrokerMessageID } from '../utils/peer-to-peer-communication-utils.js';
 
 async function peerToPeerMessageHandler(
   message: PeerToPeerMessage,
   identityClient: IdentityServiceClient,
   messageID: string,
 ): Promise<void> {
-  const { olmAPI } = getConfig();
+  const { olmAPI, sqliteAPI } = getConfig();
   if (message.type === peerToPeerMessageTypes.OUTBOUND_SESSION_CREATION) {
     const { senderInfo, encryptedData, sessionVersion } = message;
     const { userID: senderUserID, deviceID: senderDeviceID } = senderInfo;
@@ -162,6 +164,23 @@
         `Error verifying device list for user ${message.userID}: ${e}`,
       );
     }
+  } else if (message.type === peerToPeerMessageTypes.MESSAGE_PROCESSED) {
+    try {
+      const { deviceID, messageID: tunnelbrokerMessageID } = message;
+      const clientMessageID = getClientMessageIDFromTunnelbrokerMessageID(
+        tunnelbrokerMessageID,
+      );
+      await sqliteAPI.removeOutboundP2PMessagesOlderThan(
+        clientMessageID,
+        deviceID,
+      );
+    } catch (e) {
+      console.log(
+        `Error removing message after processing: ${
+          getMessageForException(e) ?? 'unknown error'
+        }`,
+      );
+    }
   }
 }
 
diff --git a/lib/utils/peer-to-peer-communication-utils.js b/lib/utils/peer-to-peer-communication-utils.js
new file mode 100644
--- /dev/null
+++ b/lib/utils/peer-to-peer-communication-utils.js
@@ -0,0 +1,13 @@
+// @flow
+
+function getClientMessageIDFromTunnelbrokerMessageID(
+  tunnelbrokerMessageID: string,
+): string {
+  const ids = tunnelbrokerMessageID.split('#');
+  if (ids.length !== 2) {
+    throw new Error('Invalid tunnelbrokerMessageID');
+  }
+  return ids[1];
+}
+
+export { getClientMessageIDFromTunnelbrokerMessageID };