Anyone had trouble retrieving email from an icloud account using an eMac running 10.3.9

I have an eMac. A bit old school but it works for me. Up until 3 days ago I was able to retrieve my email from icloud using mail. I have all the settings set up as apple suggests. Now all of a sudden it does not work. I have been receiving a meesage about my certificate being invalid. I phoned apple support and they cannot help as 10.3.9 is no longer supported. It does not seem to be a software or hardware problem at my end, as i can still retrieve emails from all my other non apple accounts. Really confused. Any body share some light on this one. Thanks