Introduction

In this article we will describe how the EMSD (Efficient Mail Submission & Delivery)[5] protocol can be used to provide powerful new messaging capabilities. The capabilities we describe are based entirely on existing technologies, and on existing open and free protocols. We will describe two major new applications:

• Use of EMSD to provide true Mobile Messaging capability to the user who habitually carries a cell phone and a PDA device, without requiring additional hardware components. In particular, the model we describe does not require the customary add-on wireless modem for the PDA, so that the cost and inconvenience of this component can be eliminated. We refer to this model as the WhiteBerry/ $\mathbf{\{Bluetooth\}}$ messaging solution.
• Use of EMSD to provide a general Mail Notification functionality, which can provide the user with immediate notification of the arrival of certain types of messages in the user's back-end Message Center.

This article is a follow-on to a previous Manifesto article entitled Use of EMSD for Mail Notification [11]. In that article we describe the Mail Notification model in technical terms; in this article we describe its implementation in a specific messaging context.

The models we describe in this paper are part of a more general industry movement which we call Operation WhiteBerry [8]. As described in Section 19.4, the Operation WhiteBerry movement is supported by a comprehensive set of development tools and resources. In particular, free open-source software implementations of the EMSD protocol are immediately available for a wide variety of end-user devices and Message Center platforms. All this software is readily available at the MailMeAnywhere open-source software distribution center at http://www.MailMeAnywhere.org.

The models we describe are thus not merely theoretical, but can be implemented immediately and without difficulty using existing software components.

Bluetooth vs. $\mathbf{\{Bluetooth\}}$

In Section 18.3 we describe how true Mobile Messaging can be implemented based on a cell phone and a PDA. A key component of this model consists of a technology for short range, low power wireless communications between the cell phone and the PDA. At present there are two candidate technologies which address this requirement: 802.11, and Bluetooth.

The 802.11 [13] standard for wireless LANs (WLANs) is an IEEE Media Access Control (MAC) specification which was completed in 1997. The latest step in the evolution of the specification has been the ratification of the 802.11b or High Rate, providing data rates of up to 11 Mbps which can reach distances of hundreds of feet. Products based on 802.11 are now available in a variety of forms, and are experiencing widespread usage. Interoperability amongst the 802.11 products is common place and certification processes such as Wi-Fi(wireless fidelity) which assurance of interoperability are in place. This widespread availability and usage has brought significant economies of scale benefits at both component and device level, greatly reducing the cost of 802.11 solutions. 802.11 does not specifically address the low power end of short range wireless communications, e.g. for communications with small battery operated devices. However it is to be expected that low power flavors of 802.11 will be developed in the future.

Bluetooth [38] is generally intended as replacement for wires and links between devices like laptops, cell phones, headsets and handheld computers. Bluetooth was intended to be a low-cost, low-power wireless technology for short-range radio communication. It has been under development for more than three years. Bluetooth provides fast and reliable digital transmission of both voice and data. Unlike infrared technology, Bluetooth is not limited to line-of-sight communication. Some Bluetooth products are available, but the price remains high. For more information visit the Bluetooth website at http://www.bluetooth.com/.

There are many in the wireless industry who argue that Bluetooth is no longer a viable option for short range wireless communications, since 802.11 is already in widespread usage and has lower cost; see for example the article Bye, Bye Bluetooth [39]. This may very well be the case for wireless communications in general, but it is not yet clear what will be the winning technology in the extremely low power short range environment. Bluetooth may yet play a role in addressing the requirements of extremely low power devices such as battery-operated cell phones and miniaturized PDAs. Furthermore, it is reasonable to expect pieces of Bluetooth technology (e.g. physical layer, usage profiles) to be merged in with 802.11 solutions.

However, this debate, and the eventual technological outcome, are irrelevant to our current purposes. What is clear is that there is a need for short range, low power wireless connectivity, and that some technology will eventually occupy this space, whether it be Bluetooth, 802.11 or something else altogether.

The model we describe in Section 18.3 requires cell phone/PDA connectivity, but it is independent of the particular technology used to accomplish this. We refer to Bluetooth in the title of this article for the sake of catchy wordplay; however the model we present is in no way locked in to Bluetooth.

Since repeated use of the wording ``Bluetooth, or similar technology for short range wireless communications'' will quickly become wearisome to the reader, we will use the notation $\mathrm{\{Bluetooth\}}$ throughout this article as shorthand for this. Specifically, we define $\mathrm{\{Bluetooth\}}$ to mean:

Bluetooth, or a Bluetooth-like technology that can provide short range, low power, inexpensive wireless communications between a cell phone and PDA.

On those occasions when we really do mean Bluetooth specifically, we will say Bluetooth.

Industry Characteristics and Trends

There are various industry characteristics and trends that act to enable or facilitate the models we describe in this paper. The following characteristics or trends are of particular relevance:

• $\mathbf{\{Bluetooth\}}$ support increasing on cell phones. Support for Bluetooth itself is becoming increasingly common on cell phones, for example to enable the use of cordless hands-free headsets and other close-proximity components. We expect that this trend will continue, and that support for Bluetooth or similar technology will eventually become the norm for cell phones.

• $\mathbf{\{Bluetooth\}}$ support increasing on PDAs. Bluetooth hardware is also becoming increasingly common on PDAs, for example to enable cordless synchronization with a desktop PC. We expect this trend to continue, and that Bluetooth or similar technology will eventually become the norm for PDAs.

• IMAP (Internet Message Access Protocol) support increasing on PDAs. IMAP Client software is becoming increasingly widespread on PDAs, for example to support e-mail synchronization of the PDA with a desktop mailbox application. We expect that IMAP support will eventually become the norm for PDAs.

• EMSD (Efficient Mail Submission & Delivery) support to increase in Message Centers. As the open WhiteBerry solution becomes widespread throughout the Mobile Messaging industry, we expect that EMSD support will increasingly be provided in Message Centers.

• Essential Mobile Messaging requirements: Unconscious carry and push-mode delivery. Market experience has now demonstrated beyond any doubt that the correct Mobile Messaging model includes two essential characteristics: unconscious carry, meaning that messaging is provided on a device that can be carried without moment-to-moment awareness of its presence; and push mode delivery, meaning that messages are delivered directly to the recipient without requiring an explicit poll or retrieval action. Any viable messaging solution must have these two characteristics.

• Cell phone and PDA a viable device configuration. The mobile professional of today can choose to carry any of a wide variety of communications and productivity devices. A common choice among users is to carry separate cell phone and PDA devices. This user may also equip himself with Mobile Messaging capability, implemented either via the cell phone, via the PDA, or by means of a specialized messaging device.

  Though other options are commonly exercised, we will assume throughout this article that the separate cell phone and PDA option is and will remain a viable and important option in the mobile marketplace.

  There already exists a large body of speculative literature describing the pros and cons of various device types and configurations, and predicting their future success or failure. The purpose of this article is not to add to this. For those who are interested, however, we provide a justification for this assumption in the appendix to this article.