Syncing Multiple Mailboxes

I have my Macbook Pro at home running Lion, my iPhone 4S and my work computer iMac running Snow Leopard. These three ways of checking my mail (which is a gmail account) don't really seem to be fully in sync with each other. A message I send at work won't show up in my sent column at home and my iPhone doesn't even have any sent messages period. A conversation started at my home computer won't show up on the others unless someone replies to it.

Sorry if this isn't the most elegant description of this problem but in summation I just wondered if I can get those three mailboxes looking and running exactly the same