diff --git a/ts/jobs/helpers/handleMultipleSendErrors.ts b/ts/jobs/helpers/handleMultipleSendErrors.ts
index 9e1b7c1e3..01bd09098 100644
--- a/ts/jobs/helpers/handleMultipleSendErrors.ts
+++ b/ts/jobs/helpers/handleMultipleSendErrors.ts
@@ -53,7 +53,7 @@ export async function handleMultipleSendErrors({
         retryAfterError = error;
         longestRetryAfterTime = retryAfterTime;
       }
-    } else if (errorCode === 508) {
+    } else if (errorCode === 508 || errorCode === 400) {
       serverAskedUsToStop = true;
     }
   });
@@ -67,7 +67,7 @@ export async function handleMultipleSendErrors({
   }
 
   if (serverAskedUsToStop) {
-    log.info('server responded with 508. Giving up on this job');
+    log.info('server responded with 508 or 400. Giving up on this job');
     return;
   }
 
diff --git a/ts/util/sendToGroup.ts b/ts/util/sendToGroup.ts
index c164858da..e0ae4f972 100644
--- a/ts/util/sendToGroup.ts
+++ b/ts/util/sendToGroup.ts
@@ -731,6 +731,11 @@ export function _shouldFailSend(error: unknown, logId: string): boolean {
   //   SendMessageChallengeError
   //   MessageError
   if (isRecord(error) && typeof error.code === 'number') {
+    if (error.code === 400) {
+      logError('Invalid request, failing.');
+      return true;
+    }
+
     if (error.code === 401) {
       logError('Permissions error, failing.');
       return true;