When you check your calendar Monday, June 7, you may feel a bit like Alice just after falling down the rabbit hole: The landscape will be different.

The Oracle Calendar service used by faculty, staff and many graduate students will have been replaced by a Microsoft Exchange system. Over the weekend beginning June 4, Cornell Information Technologies (CIT) will move most of the data stored in the Oracle system to an Exchange server.

This spring, nearly all faculty and staff switched from the old Cornell postoffice system to the Exchange server for e-mail. As of May 11, CIT reported, there were 19,600 Exchange users. With the switch from Oracle Calendar to Exchange, e-mail, calendar and contacts will work together seamlessly -- if you're in the right rabbit hole.

Windows users running Outlook 2007 and Internet Explorer 6 or higher and users of Intel Macs running Snow Leopard will be able to integrate the three services. But if you're on an older Mac or Windows machine or running Linux, things may get a bit clunky. Older versions of Apple's iCal won't sync with the Exchange calendar. Mac users have the option of using Microsoft Entourage 2008 -- the mail client included in the Microsoft Office suite -- to get the same integration of e-mail, calendar and contact information as Windows Outlook users (Microsoft has promised a Mac version of Outlook). Entourage also will let you synchronize the Exchange calendar with iCal. But this means giving up Apple Mail as your e-mail client. Some critics also grumble that Entourage is slow. Users of older Macs can use the latest version of Entourage: Download Entourage 2008 Web Server Edition, which is not provided by Microsoft's Auto Update.

Another option for all users is Outlook Web Access, https://exchange.cornell.edu/owa/, which replaces CIT's WebMail and gives users access to their mail, calendar and contacts through any Web browser. But unless you're using Internet Explorer 6 or better on Windows, you get the "light" version, which displays only one day at a time and has other serious limitations. A newer version of the Exchange server that is expected to be installed later this year should correct these problems, CIT says.

Although meetings, tasks, contacts and other data will be copied to the new server, permissions will not. By default, your calendar will be invisible to anyone else unless you set it to be readable. If you have delegated management of your calendar to someone else, you will have to redelegate. Only users of Outlook 2007 and iCal 4 will be able to do this directly; it cannot be done through OWA. You will have to visit someone with a Windows or Snow Leopard machine. Another option for users of older Macs is to fire up Entourage 2008 just once to make the changes.

Mobile users, some of whom have had to use complicated workarounds to connect to Oracle Calendar, will find using the Exchange calendar simpler, CIT says. They will have to make some changes, however. Instructions will be posted on the CIT website May 24.

Students, meanwhile, have been switched to Google Apps for Education, locally known as Cmail, which provides e-mail, a personal calendar and collaboration tools. Graduate students who need to schedule meetings with faculty and staff may request Exchange accounts beginning in June.

CIT offers workshops and online training in the use of the new services. Start at http://www.cit.cornell.edu/training/exchange/index.cfm. For detailed information on the calendar changeover go to http://www.cit.cornell.edu/facstaff_email/calendar/.