diff --git a/scraibe/email_sender.py b/scraibe/email_sender.py
index 642451f..349a03c 100644
--- a/scraibe/email_sender.py
+++ b/scraibe/email_sender.py
@@ -221,7 +221,13 @@ def send_email(
     msg["To"] = ", ".join(to_list)
     if cc_list:
         msg["Cc"] = ", ".join(cc_list)
-    msg["Subject"] = subject
+    
+    # Ensure subject is never blank
+    if not subject or not subject.strip():
+        logger.warning("Subject was blank; using default subject.")
+        subject = "ScrAIbe: Your transcript is ready"
+    
+    msg["Subject"] = subject.strip()
 
     # Attach plain text
     msg.attach(MIMEText(body, "plain"))
diff --git a/scraibe/tasks.py b/scraibe/tasks.py
index aa90c9a..a7ca0b6 100644
--- a/scraibe/tasks.py
+++ b/scraibe/tasks.py
@@ -166,13 +166,22 @@ def send_success_email(
     Falls back to a safe default if the env var is missing or blank.
     """
     # Read subject from environment; never allow blank
-    subject = (os.getenv("EMAIL_SUBJECT_SUCCESS") or "").strip()
+    raw_subject = os.getenv("EMAIL_SUBJECT_SUCCESS")
+    subject = (raw_subject or "").strip()
+
     if not subject:
         subject = "ScrAIbe: Your transcript is ready"
-        logger.info("EMAIL_SUBJECT_SUCCESS not set or blank; using default subject.")
+        logger.info(
+            "EMAIL_SUBJECT_SUCCESS not set or blank; using default subject: %s", subject
+        )
     else:
         logger.info("Using EMAIL_SUBJECT_SUCCESS: %s", subject)
 
+    # Final guard: ensure subject is never empty
+    if not subject:
+        subject = "ScrAIbe: Your transcript is ready"
+        logger.warning("Subject was empty after reading; forced default subject.")
+
     body = (
         "Hello,\n\n"
         "Your transcription is ready.\n\n"