GoDaddy Virtual Dedicated Server Email Problem

Hi, I have an e-commerce site hosted on a go daddy dedicated server. One month ago the server stopped sending out contact form emails and email confirmations from the shopping cart check-out. The code is all fine, I am not sure what the problem is. I checked the email logs and it should that emails have been sent but I did not receive them. If you have experience troubleshooting and working on a dedicated server and are a php programmer please send me a note. You will have to test and find out the issue. Please have experience working on godaddy servers.