Since it sounds like noone else has responded to your question, I'll give it a shot; even though I don't use Evolution. If Evolution stores emails in clear text, and I bet it does then this might work. You could use grep to try and locate one of your past emails some thing like: grep -rlF TEXT ~/* (From the command prompt.) Replace TEXT with an unusual sentance in one of the emails in your folders. This should give you a sense of where the file is located. Once you figure out where the folders are you should be able to simply copy them to your server. I've done this with Thunderbird (from a win machine to a Linux box no less) and it worked well. If all else fails you might be able to find help on the evolution website.
I need to find a way to move this stuff so I can get a new dual-boot system (windows/linux). I can't even figure out which directory all this Evolution stuff lives in.