04/17 Update: sends email to each IT Staff from email ingestion ticket

app/services/notification_service.py

@@ -107,18 +107,34 @@ def create_notification(user_id, notif_type, title, message, ticket_id=None, lin
 
 def send_email(subject, recipients, html_body):
     """
-    Send an email in a background thread so it never blocks the request.
+    Send an email in a background thread so it never blocks the caller.
 
     Flask-Mail opens an SMTP connection synchronously. Running it in the main
     request thread means a slow or failing SMTP server delays the entire
     response — including the WebSocket notification push that follows.
-    Using a daemon thread isolates SMTP failures from the request lifecycle.
+    Using a background thread isolates SMTP failures from the request lifecycle.
+
+    Thread daemon mode
+    ------------------
+    When called from a web request context, the thread is spawned as a daemon
+    (daemon=True) so it does not prevent the server process from exiting cleanly.
+
+    When called from an APScheduler background job (no active request context),
+    the thread is spawned as a non-daemon (daemon=False).  Daemon threads are
+    killed as soon as the parent thread exits — since the APScheduler job thread
+    finishes quickly, a daemon email thread is terminated before SMTP delivery
+    completes, causing silent email loss.  A non-daemon thread survives until
+    the SMTP handshake finishes regardless of the job thread's lifetime.
     """
     from threading import Thread
-    from flask import current_app
+    from flask import current_app, has_request_context
 
     app = current_app._get_current_object()   # real app, not the proxy
 
+    # Determine daemon mode based on whether we are inside a live HTTP request.
+    # APScheduler jobs and other background callers have no request context.
+    is_daemon = has_request_context()
+
     def _send():
         with app.app_context():
             try:
@@ -128,7 +144,7 @@ def send_email(subject, recipients, html_body):
             except Exception as exc:
                 logger.error(f'[EMAIL ERROR] Failed to send "{subject}" to {recipients}: {exc}')
 
-    t = Thread(target=_send, daemon=True)
+    t = Thread(target=_send, daemon=is_daemon)
     t.start()
 
 
@@ -502,6 +518,10 @@ def send_satisfaction_survey(ticket):
                     f'recipient={creator_email}: {exc}', exc_info=True
                 )
 
-    t = Thread(target=_send, daemon=True)
+    # Mirror the daemon-mode logic from send_email(): non-daemon when called
+    # outside a request context (e.g. from the SLA APScheduler job) so the
+    # thread is not killed before SMTP delivery completes.
+    from flask import has_request_context
+    t = Thread(target=_send, daemon=has_request_context())
     t.start()
     logger.info(f'[SURVEY] Email thread started for ticket_id={ticket_id}')