save email whose bounce info can't be parsed for debugging

app/email_utils.py

@@ -1350,3 +1350,18 @@ def parse_full_address(full_address) -> (str, str):
         raise ValueError
 
     return full_address.display_name, full_address.address
+
+
+def save_email_for_debugging(msg: Message) -> str:
+    """Save email for debugging to temporary location
+    Return the file path
+    """
+    if TEMP_DIR:
+        file_name = str(uuid.uuid4()) + ".eml"
+        with open(os.path.join(TEMP_DIR, file_name), "wb") as f:
+            f.write(msg.as_bytes())
+
+        LOG.d("email saved to %s", file_name)
+        return file_name
+
+    return ""

email_handler.py

@@ -124,6 +124,7 @@ from app.email_utils import (
     parse_full_address,
     get_orig_message_from_yahoo_complaint,
     get_mailbox_bounce_info,
+    save_email_for_debugging,
 )
 from app.log import LOG, set_message_id
 from app.models import (
@@ -1261,7 +1262,7 @@ def handle_bounce_forward_phase(msg: Message, email_log: EmailLog):
             email=mailbox.email, info=bounce_info.as_bytes().decode(), commit=True
         )
     else:
-        LOG.w("cannot get bounce info")
+        LOG.w("cannot get bounce info, debug at %s", save_email_for_debugging(msg))
         Bounce.create(email=mailbox.email, commit=True)
 
     LOG.d(
@@ -1489,7 +1490,7 @@ def handle_bounce_reply_phase(envelope, msg: Message, email_log: EmailLog):
             commit=True,
         )
     else:
-        LOG.w("cannot get bounce info")
+        LOG.w("cannot get bounce info, debug at %s", save_email_for_debugging(msg))
         Bounce.create(email=sanitize_email(contact.website_email), commit=True)
 
     # Store the bounced email
@@ -1753,7 +1754,7 @@ def handle_transactional_bounce(envelope: Envelope, msg, rcpt_to):
                 commit=True,
             )
         else:
-            LOG.w("cannot get bounce info")
+            LOG.w("cannot get bounce info, debug at %s", save_email_for_debugging(msg))
             Bounce.create(email=transactional.email, commit=True)