Although the anticipated explosion of application service providers (ASPs) came far short of industry projections, and the majority of ASPs have either gone out of business or have been absorbed, some ASPs are succeeding by offering focused solutions, which quite often include Exchange-based messaging services. Unfortunately, Exchange 2003’s basic architecture remains the same as Exchange 2000, so ASPs will still not get the levels of scalability and message database isolation they seek. However, the new version does contains some improvements that could benefit ASPs, especially:

Better and greater choice of mail clients. With Exchange 2000, ASPs were constrained in the mail clients they could support. Outlook Web Access (OWA) is easy to offer since it runs in a Web browser, but it is slow and lacks support for many Exchange features. Connecting Outlook or Outlook Express clients to the Exchange Server using the Post Office Protocol 3 (POP3) or Internet Message Access Protocol 4 (IMAP4) protocols is more scalable than the regular Outlook’s native Messaging API (MAPI) protocol, but these protocols do not give users access to extended Exchange features, such as calendar, contacts, and tasks. Most customers want the full Outlook client capabilities but because MAPI generates more network traffic and is difficult to send through firewalls, it is usually only feasible when used over a high-speed virtual private network (VPN) connection. Regular Outlook also puts higher loads on the server than POP3/IMAP4 clients because it cannot use a front-end/back-end server configuration, which distributes the workload by processing the POP3/IMAP4 protocol on separate servers from the one that processes mailbox and folder storage.

Although the anticipated explosion of application service providers (ASP) came up far short of industry projections and the majority of ASPs have either gone out of business or have been absorbed, some ASPs are succeeding by offering focused solutions, which quite often include Exchange-based messaging services. Exchange 2003 contains some further improvements that could benefit ASPs, but since the basic architecture remains the same as Exchange 2000, ASPs will still not get the scalability and message database isolation they seek.

ASPs should benefit from the following Exchange 2003 features:

Better and greater choice of mail clients. With Exchange 2000, ASPs were constrained in the mail clients they could support. Outlook Web Access (OWA) is easy to offer since it runs in a Web browser, but it is slow and lacks support for many Exchange features. Outlook or Outlook Express clients connecting using the Post Office Protocol 3 (POP3) or Internet Message Access Protocol 4 (IMAP4) protocols are more scalable than regular Outlook, but users lack access to extended Exchange features, such as calendar, contacts, and tasks. Regular Outlook over its native Messaging API (MAPI) connections is what many customers want, but because it is so chatty over the network and difficult to send through firewalls, it is usually only feasible when used over a high-speed virtual private network (VPN) connection. Regular Outlook also puts higher loads on the server than POP3/IMAP4 clients because it cannot use a front-end/back-end server configuration to distribute workloads.