Q: Hidden email folders 2008 iMac

I have a 2008 iMac which recently died.  I removed the hard drive and mounted it in an external dive case.  I purchased a new iMac 27" and plugged the old drive into the new Mac.  I was able to transfer in all the data I need  from the old Mac's hard drive except for the emails and email folders.  I have read that the emails and email folders on the 2008 Mac are hidden files, but where?  I have searched that hard drive up and down, I can't find them.  Any suggestions?  Thanks for your help.