I usually do all my mails in two parts. I use my laptop and download all the incoming mails to it. I disconnect and take care of any replies I have to reply to, and then I'll reconnect and send all those replies, so all the reading and replying is done offline.

If uploading a picture to facebook or something I'll resize it before sending so it's not taking forever to transmit. And don't forget to disconnect if you are using your own machine, son't go to dinner with it still connected checking mail or whatever every few minutes. Remember you are charged for connected time, not usage time, even if you don't send or receiving anything on the internet, your minutes are still ticking away.