Mobility has been on my mind a lot lately. Seemingly every week, some company introduces a new wireless device with claims that the product can seamlessly deliver email to you, wherever you are. Whether this type of availability is desirable is open to discussion—my wife and I certainly have different opinions—but clearly wireless, always-on email access is a growing trend.

The device that started the mobile wars is Research In Motion's (RIM's) BlackBerry (affectionately known as "the homewrecker" by several engineers I know). The BlackBerry comes in several forms, ranging from a familiar pager-like device to a combination pager/Global System for Mobile Communication (GSM) mobile phone. You can relay email to a BlackBerry device through a desktop software package, which requires that you keep Outlook running, or through the BlackBerry Enterprise Server, a standalone server that relays email for multiple Exchange Server users. Either method relays email to the devices through a mobile data network that covers much of North America, Asia, or Europe. The BlackBerry is simple to use and does its basic job—providing email access—extremely well.

Since the BlackBerry's introduction, many other mobile-access products have hit the market. These products fall into three general categories: PDAs with integrated wide-area wireless access, PDAs with local-area wireless access, and combination PDA/cellphone devices.

The best-known examples of products in the first category are the venerable Palm VII/VIIx and its replacement, the Palm i705. These devices typically require you to use a product-specific email provider, which means they don't work with Exchange and are largely useless for corporate email environments. Don't depend on them for accessing your Exchange servers unless you want to buy Palm's new Tungsten product, which provides Palm i705 access to Exchange-hosted email accounts.

PDAs with local-area wireless access use Wi-Fi (the 802.11b wireless standard) or Bluetooth to connect to existing wireless networks. Some devices, such as Hewlett-Packard's (HP's) iPAQ 3970 and Toshiba's Pocket PC e740, feature built-in wireless connectivity; others, such as Handspring's Visor line and older iPAQs, can support wireless-expansion modules. This category of PDAs generally uses IMAP or POP to communicate with Exchange servers, so you'll need to enable one or both of those protocols to support mobile users. Some devices support Pocket Outlook and so can use Outlook natively through a VPN or when directly connected to your corporate intranet.

Combination PDA/cell phone devices, such as Kyocera's Smartphone line, AT&T Wireless's Siemens SX56, and Audiovox's Thera PDA2032, also often use IMAP or POP to communicate with Exchange. Pocket PC-based devices can use Microsoft Mobile Information Server to provide seamless wireless access to native Exchange features such as calendaring and tasks. (Be aware that although Mobile Information Server works closely with Exchange, there are a lot of subtleties to setting up the product properly. See the Resources section below for more information about deploying Mobile Information Server.)

Which devices are best for your users depends on several factors. The overriding factor, of course, is what users need the device for. The BlackBerry originally became popular because it does a fine job of delivering email, plain and simple. Although newer models support calendaring and tasks, the BlackBerry still isn't as tightly integrated with Outlook's non-email capabilities as most users might like. Palm OS-based PDAs do a grand job of synchronizing information with the Outlook desktop—as long as users can connect to it. However, the wireless Palm.Net email service is expensive and limited compared with the combination of Exchange and Outlook.

Integrated devices probably hold the most promise. I've been toting around a Kyocera Smartphone for almost 2 years, and its ability to sync with all my Outlook data and still get IMAP email from just about anywhere in North America has been a real winner. Devices that use the Pocket PC Phone Edition or Smartphone platform (two separate but related Microsoft initiatives) bear watching, too, because they combine the familiar Windows interface with a range of desktop-like features (including the ability to easily open Microsoft Word and Microsoft Excel attachments) and wireless connectivity.

If you haven't yet deployed wireless devices, you're in a good position to study the alternatives and their effect on your Exchange servers (e.g., you might need to offer POP or IMAP service, you might run into support hassles involving mobile-device users who travel to obscure locations). New vendors and products are popping up all the time, so you have plenty of choices. Just remember—once your users go mobile, they'll never want to go back.