E-mail’s future is the focus of a debate April 20 in San Francisco. Danny O’Brien of the Electronic Frontier Foundation (EFF) and Esther Dyson, editor of CNET’s technology industry newsletter will discuss the prospects of e-mail taxation and potential consequences of paid e-mail. Would the Internet deteriorate as a platform for free speech? Would spam or phishing decline or increase? The event will be moderated by Open Source Applications founder Mitch Kapor at 7 p.m. Thursday, April 20 at the Roxie Film Center, 3117 16th St., San Francisco. The fundraiser is open to the public. While the suggested donation is $20, no one will be turned away for lack of funds, according to the EFF.