Mail.app not working. Need to backup before reinstalling.

Hi,

My mail.app has stopped responding. No matter what I do it crashes every time I try to open it. Talking to some experts, they advised me to reinstall the application. I am worried as I have not setup the Time Machine backup and there are some email folders that are important. I have no backup of them. I wanted to know how can I backup the email folders and contact lists as well if I am going to reinstall the mail.app application?

Please help.