Even as Exchange Server 5.0 goes gold, Microsoft is hard at work on the next two releases of the Internet Messaging server. Version 6.0, code- named "Iridium," will support a Web-browser front end, will boost storage capacity from 16 Gb to 16 Terabytes (Tb), and will add native support for the IMAP4 remote mail access protocol. The 16 Gb storage limit was the major source of complaints from customers. Iridium will ship by the end of the year. A later release of Exchange, code-named "Platinum," is due in 1998