Fix for email sending (#9526)

* Fix for email sending

- Extract valid email for user
- Do not send if email not configured for user

* Improve email address filtering logic

* Fix return type hint

.devcontainer/docker-compose.yml

@@ -24,8 +24,6 @@ services:
     volumes:
       - ../:/home/inventree:z
       - /tmp/.X11-unix:/tmp/.X11-unix
-    ports:
-      - 8000
 
     environment:
       INVENTREE_DB_ENGINE: postgresql