Email stopped working

[Larrycleve]

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 seems to receive items but can't send. She used to get a sound when incoming mail was finished which has stopped. 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?