The following article will get your Microsoft Exchange 2010 mailbox setup on your iPhone, iPad and iPod using the Activesync technology.
Let's take a look at the following steps below to get you going:

Note: Your device must be a 3G, 3Gs, and with a 4.0+ iOS.

Note: Before we get started, please be sure your administartor has purchased you an Activesync license and assigned to your email address.

Note: We recommend turning off wi-fi on your device before proceeding.

1. First thing you'll want to do is from your home screen, tap the Settings icon on the iPhone.
   
   
2. After tapping your Settings icon, you'll Tap Mail, Contacts, Calendars, Add Account then Microsoft Exchange.
   
         
3. The Exchange setup screen will open; you'll then enter the following information:
   • Email - Enter your entire email address (e.g., [email protected]), using all lowercase letters.
   • Domain - leave this field empty.
   • Username - Enter in your entire email address.
   • Password - Enter in the password for your email account.
   • Description - Enter a descriptive name for your account (e.g., My Work Account). This description will only be visible to you.
   
4. Tap the Next button and the device will attempt to verify the account. You may receive an "Unable to Verify Certificate message," go ahead and Tap the Accept button.
5. The device will than continue verifying the account. Once complete, tap the Server field, and enter in "connect.emailsrvr.com" minus the parenthesis.
   
   
6. Tap the Next button and the device will then try to create a secure (SSL) connection to your Exchange server. When connected, you'll see check marks along your settings to confirm that your account has been verified.
   
   
7. Tap the ON/OFF buttons to select which information to synchronize with the Exchange server and then tap the Done button when finished.
   
   

Note: Your iPhone may take a moment to sync all your information depending on how much you have on the Exchange server. To learn more about the mail settings on your device tap Settings from the home screen, than Mail, Contacts, & Calendars and than select your account. You'll be able to customize how much data you would like to sync from the server.