Exchange versus POP3

Regularly we receive the question: "What is so special about Exchange that justifies the monthly fee?" or
"Why spend money on Exchange, when I can get my email for free using POP or IMAP?".

Ok. Let us first briefly explore POP and IMAP
(full comparison here):

POP is short for Post Office Protocol, a protocol used to retrieve e-mail from a mail server. Most e-mail applications/e-mail clients use the POP protocol, although some can use the newer IMAP (Internet Message Access Protocol).

IMAP is also a mail access protocol that enables you to read and store messages. Unlike POP3, IMAP provides full-server side storage and public folders which provides all of the functionality offered by the email component of Exchange.
But IMAP is far from a complete e-mail solution.

Back to the initial question.
First of all, we can not compare the functionality of a full email and collaboration system (Exchange) by comparing it to a mail access protocol (IMAP, POP) as if they are equals.
IMAP is not and will never be a replacement for Exchange. It is an open protocol for the reading and filing of email.

Outlook and Exchange provide a complete collaboration system, Outlook offers integration with SharePoint and Dynamics (CRM). Outlook is built for Exchange.
Want shared calendars, meeting facilities, the Global Address Book, tasks etc?
Want a iPhone, Windows Mobile or Blackberry and push technology (BES, ActiveSync)?
You need Exchange.

Microsoft Exchange Server is Microsoft's enterprise (large-scale) e-mail and electronic messaging server software.
While Exchange originated as an e-mail system, it has evolved to support calendaring, meeting and task management, web-based e-mail access, and other business support features.

It's a business e-mail platform, not a protocol of retrieving email. It's the industry standard. And now with the ever-increasing number of mobile devices/handhelds like BlackBerry, iPhone and Windows Phone devices, the need is there to keep everything in Sync.