It’s almost unthinkable to be in Cannes for a few days and not have access to your e-mails. Midem obviously has Internet connections for visitors, although you usually have to stand in a queue. If you want a more accessible connection, you should think about taking a WiFi subscription. SFR is the supplier within the Palais, but I’ve had no luck finding out how much it costs. The site simply says that you turn your computer on, find the network and follow the payment process (without actually giving a price). The SFR site provides no details. The hotels obviously also have connections you can use. But if you’re staying outside town, that doesn’t help much during the day.
Amongst the prepaid solutions, the easiest one I could find information about is Orange. They offer 1, 3, 10 and 30 hour packages you can buy in Relay newsagents or online from the Orange site (in French but quite clear). I’ll probably opt for the 3-hour option for €10 (with 50% extra for €1 if you purchase before January 15), which should be enough to grab e-mails, work offline and then send them out afterwards. If you have experience using other prepaid WiFi solutions in France, why not drop a line about it in the comments?