Many businesses prefer IMAP over POP3 because IMAP provides greater control over message management, such as keeping the mail folders synchronized as mail is moved on any client. The iPhone will connect to the IMAP server and detect most settings automatically, making setup easy in most cases.
You can adjust the SSL settings, IMAP path prefix, server port, and other such settings by scrolling down to the Advanced portion of an individual mail account’s setup area. Note that the iPhone’s SSL options have been significantly enhanced from the first iteration’s number-only token scheme.
What you can’t do with the iPhone -- out of the box, anyhow -- is get the BlackBerry’s push-based approach to e-mail, in which the mail server sends messages to the device rather than requiring the device to query the server to gain access to new messages. This push-based approach makes it harder for someone to spoof the e-mail server. To push e-mail to an iPhone (or most other mobile devices), you need a mobile server such as those from Visto and Synchonica; these integrate with your Exchange or Domino server.
The iPhone also doesn’t support Microsoft’s Direct-Push approach (aka ActiveSync on Windows Mobile and Palm OS devices), which leaves the connection between the OWA (Outlook Web Access) server’s mail port and the mobile device open so that new messages are instantly visible. (The iPhone does use OWA as its connection to Exchange, just as Microsoft’s Entourage e-mail client does for the Mac OS.) Instead, you’ll have to live with the iPhone’s periodic mail checks (15 minutes is the shortest period, though you can easily find SSH hacks on the Web to reduce that window.) Rumors have been flying for months that Apple has licensed ActiveSync from Microsoft; maybe we’ll find out on Thursday whether that rumor is true.
Accessing calendars and other shared data
The biggest issue Exchange and Notes shops will face in business-enabling the iPhone is providing access to calendars, address books, and other PIM data beyond e-mail.
Calendars and contacts can be synchronized between Exchange and the iPhone, but this must be done through iTunes, meaning you will need a PC or Mac to act as an intermediary.
For Windows (XP or Vista) shops tapping Outlook 2003 or 2007, syncing is straightforward through iTunes. Connect the iPhone to your intermediary PC and select it in iTunes’ Devices list. Open the iTunes device Info pane and choose the calendars and contact sources you want to sync. If you have problems, consult Apple’s common fixes.