diff --git a/CHANGELOG.md b/CHANGELOG.md
index 79508b9..73474cb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,6 +20,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Convert `frontend/jest.config.js` to `jest.config.mjs` using ES module `import`/`export` syntax to resolve ESLint `@typescript-eslint/no-require-imports` error.
+- Suppress noisy `ignored untagged response` INFO log lines from `aioimaplib` in Celery workers by setting the `aioimaplib` logger to WARNING level in `celery_app.py`.
+- Eliminate `file_cache is only supported with oauth2client<4.0.0` warnings by passing `cache_discovery=False` to `googleapiclient.discovery.build()` in `gmail_service.py`.
 
 ## v0.5.0 (2026-03-28)
 
diff --git a/backend/app/services/gmail_service.py b/backend/app/services/gmail_service.py
index 48a4149..e848ae2 100644
--- a/backend/app/services/gmail_service.py
+++ b/backend/app/services/gmail_service.py
@@ -84,7 +84,9 @@ class GmailService:
     def service(self):
         """Lazy-initialize the Gmail API service."""
         if self._service is None:
-            self._service = build("gmail", "v1", credentials=self.credentials)
+            self._service = build(
+                "gmail", "v1", credentials=self.credentials, cache_discovery=False
+            )
         return self._service
 
     async def inject_email(
diff --git a/backend/app/workers/celery_app.py b/backend/app/workers/celery_app.py
index b59609d..9ae8dc7 100644
--- a/backend/app/workers/celery_app.py
+++ b/backend/app/workers/celery_app.py
@@ -10,6 +10,9 @@ from app.core.config import settings
 
 logger = logging.getLogger(__name__)
 
+# Suppress noisy INFO-level "ignored untagged response" messages from aioimaplib
+logging.getLogger("aioimaplib").setLevel(logging.WARNING)
+
 # Create Celery app
 celery_app = Celery(
     "inboxconverge",
diff --git a/docs/TODO.md b/docs/TODO.md
index 155921b..e5b03a4 100644
--- a/docs/TODO.md
+++ b/docs/TODO.md
@@ -4,6 +4,7 @@ Comprehensive task breakdown for repository improvements and production readines
 
 ## ✅ Recently Completed
 
+- [x] **Log noise reduction**: Suppressed `ignored untagged response` INFO messages from `aioimaplib` in Celery workers (set logger to WARNING). Eliminated repeated `file_cache is only supported with oauth2client<4.0.0` warnings from the Gmail API client by passing `cache_discovery=False` to `googleapiclient.discovery.build()`.
 - [x] **ESLint fix**: Converted `frontend/jest.config.js` to `jest.config.mjs` (ES module syntax) to resolve `@typescript-eslint/no-require-imports` lint error.
 - [x] **Codecov integration**: Added Codecov coverage reporting with `CODECOV_TOKEN` authentication. Set up Jest for frontend tests with lcov coverage, updated CI to collect and upload both backend (XML via pytest-cov) and frontend (lcov via Jest) coverage reports to Codecov with separate `backend` and `frontend` flags.
 - [x] **IMAP: fix all emails appearing empty** — `aioimaplib` stores RFC822 literal data as `bytearray`, not `bytes`. The extraction loop was checking `isinstance(line, bytes)` which returns `False` for `bytearray`, so every email body was silently skipped. Fixed to accept both types and convert to `bytes`. Affected T-Online, GMX, and all IMAP accounts.