Software :: Email Stopped Working Because Cannot Send And Recieve The Mails?

I'm helping my mother who has an old mac laptop. I'm not familiar with macs so please bear with me. Her email has stopped working. She's using OS 10.3.9. It's apple's email app. I notice that when trying to send it sometimes says that it timed out on port 25. She seems to receive items but can't send. She's sent things to me which haven't gotten through. She used to have a percentage bar and a sound when mail was sent which has stopped. She has full bars for her wireless connection and safari browses the internet fine. What should I be looking for?