Configure Outlook Express to connect to your Exchange account as an IMAP account. This will work if IMAP emulation is enabled on the Exchange server (which it is by default).
First, you should be able to ping the Exchange server and logon to the domain where your Exchange account exists.... if successfull then do the following.
Add a mail account in Outlook Express
Specify IMAP
Use the pingable exchange server name or IP address as the IMAP and SMTP server.
For IMAP client authentication use your domain username and password as your IMAP account logon in the following format:
username=<domain>\<username>
password=<domain account password>
NOTE: Don't check secure authentication unless you fail to connect.
If successfull Outlook Express will authenticate you to your domain account and access your exchange mailbox as an IMAP mail account.
If for some reason your PC cannot logon to the domain of the exchange account, but for some reason you can still ping the mail server then use this IMAP account username format ....
\\\\<domain>\\<domain>\<username>
NOTE: As an IMAP account ... folders will remain on and be viewed from the mail server. Ask your adminsitrator about Outlook Web Access - this might be an easier alternative to IMAP if OWA is available.
<edit> I forgot to mention... if your tryign to use Windows CE's version of Outlook Express then change all the username backslashes to foreward slashes. (Only Windows CE .. not a problem with PocketPC).