Apart from MAPI, the other major client families are:
IMAP4: An Internet client access protocol that is used by most inde-
pendent clients such as Eudora. Also used by Microsoft’s Outlook
POP3: An earlier Internet client access protocol that provides a lower
level of functionality.
HTTP: The best-known web protocol and used by clients such as
Outlook Web Access.
ActiveSync: Microsoft’s access protocol for mobile clients such as
SmartPhones and PDAs.
When you approach a design project for Exchange, you have to under-
stand what clients are going to be used and why. Each client poses its own
deployment and management challenges and they have their own implemen-
tation and support costs. Clients will change over time and updates will
arrive, but you shouldn’t worry too much about having to update client ver-
sions after the project starts, because in many cases, email client software is
tied to desktop upgrades. Except for small groups, it’s just too expensive to go
and deploy a new version of an email client unless it’s part of a planned regu-
lar desktop refresh. Thus, many companies upgraded to Ofﬁce 2003 (and
therefore Outlook 2003) as part of their move to Windows XP on the desk-
top and the same thing is likely to happen with Ofﬁce 2007 and Vista.
Another reason why you shouldn’t worry too much about client versions is
that Microsoft has an excellent record of supporting older clients in new ver-
sions of Exchange. Indeed, you can connect the oldest MAPI client (the
“Capone” client or the “Exchange Viewer”) distributed with Exchange 4.0 to
Exchange 2007. While you won’t be able to take advantage of features that
newer clients can use, such as cached Exchange mode, you will be able to
send and receive email. Almost every browser can connect to Exchange 2007
and run Outlook Web Access, and even the oldest POP3 client can connect
to Exchange 2007.
After your deployment is complete, the next challenge is to deﬂect all
the user demands to connect the latest and greatest gadgets to Exchange. In
fact, the technical challenge is not difﬁcult because most of the PDAs,
phones, and other email-capable devices that appear use IMAP4, POP3, or
even ActiveSync, if the manufacturer has licensed it from Microsoft. The
challenge is support from the initial connection to the inevitable problems
that occur as users attempt to download email, upload email, synchronize
their contacts and calendars, and use applications such as Windows Live
Messenger. The help desk has probably never seen the devices that users want