The functionality of Sendmail and Exchange are quite different, but I wouldn't say that any features are necessarily "missing" from Sendmail. Sendmail was designed to do one job extremely well: reliably deliver large volumes of email messages across the Internet. Microsoft Exchange and similar products such as Lotus Notes, Scalix and Novell Groupwise are messaging and collaboration servers that are designed to address a broader set of functionality beyond email delivery. Examples of the additional functionality in messaging and collaboration servers include advanced email functionality, group calendaring and scheduling, server-based email storage, file/document sharing, contact management and other collaboration features.
Messaging and collaboration servers tend to be deployed in businesses and other organization that seek increased employee and organizational productivity by sharing a range of information. Many organizations that deploy messaging and collaboration servers also use sendmail as the message transfer agent (MTA) for managing inbound and outbound email to the Internet. Sendmail is the leading MTA used by organizations to route email messages across the Internet.
This was first published in September 2004