The 800-pound gorilla of business e-mail applications, commanding, by some counts, as much as 60% of the market.
Exchange (the server software) runs $1,299 per copy. Outlook 2003 can be bought alone ($109 per license or user) or in a Small Business Edition ($449) and with Microsoft Office.
Drag-and-drop e-mail directly into a calendar; flag crucial e-mails for follow-up; seamless integration with smart phones and PDAs. A huge number of add-on applications are available.
A junk mail filter blocks any spam missed by other layers of defense. You can also set up e-mail white and black lists. Automatic updates allow you to upgrade online--a necessity for keeping ahead of hackers.
It does a lot of stuff well. When coupled with Exchange, Outlook is a powerful information manager that allows you to organize and coordinate e-mail, contact lists, tasks, and calendars.
It's vulnerable. More viruses, Trojan horses, worms, and malicious code are aimed at Outlook than at any other e-mail program. Plus, all that calendaring and task-management stuff can make it overwhelming for the person who just wants to send and receive e-mail.