Here's how to connect using IMAP4 / Exchange.
First, as stated before, port 993 MUST be open on the firewall. You don't need both 143 and 993 open. Pick one, and choose SSL on or off accordingly, (143 is non-SSL, 993 is SSL).
The exchange server must have the IMAP service running (right click my computer on the server, choose manage, go to services and applications, then services. Find the Microsoft Exchange IMAP service on the right, right click and go to properties, then set startup type to automatic. Make sure the service is currently started.
Now for the iphone:
From the home button, go to settings, then Mail. Add a new account. . . the settings should look like:
Account : ON
Name : John Doe
address :
johndoe@domain.com
description : John's e-mail account.
Incoming Mail Server:
Host Name : mail.domain.com (enter your e-mail domain here. This is NOT always the same as your OWA, it's whatever domain name points directly to your server. Hint: if you don't know it, check to see what the MX record is named with your domain registrar)
User Name : johndoe (or whatever username format you use, as mentioned in earlier post)
Password : password
Outgoing server:
Same as above typically. Sometimes you are required to use a different SMTP server. . . if this is the case, enter that information given to you by that ISP.
Under the advanced button:
Mailbox Behaviors and Deleted items - (all personal preference, none of these will prevent you from getting e-mail).
Settings: incoming must use SSL and outgoing must use SSL depends on which IMAP port you chose to open (see above).
Authentication : password. I had this set to md5 challenge / response and it automatically changed it, so you may not have to set this manually.
IMAP path prefix. I didn't change this, but if you change the IMAP path in Exchange, you must change it here.
NOTE: I did this setup with a server that was behind a Sonicwall once. I enabled the IMAP4 service on the firewall but wasn't getting mail. I went back and looked at the logs on the Sonicwall and found that it only opened 143. I had to go back in and manually add 993 and take out the 143.