1. Open the Settings App on your phone:
2. Inside of Settings, scroll down and select "Mail, Contacts, Calendars":
3. Under Accounts, select the "Add Account" option:
4. In the account type selection screen, select "Exchange":
5. In the Account Information screen, fill in your information accordingly. Description is totally up to you, you can put "work email", "Commonwealth", "CMW"; whatever you want to label this account to distinguish it from any other mail accounts you have on your device.
6. Click Continue to move on with setup:
7. For server, type webmail.interpublic.com. For domain, type IPGNA. For username, type your first.last user name.
8. After pressing "Next", you'll choose what services to sync with your phone. Press Save to save settings and complete setup.
NOTE: If you choose to sync Contacts with your Commonwealth account, it may make your Commonwealth account your default account for new contacts. So, any contacts that you enter into your phone will go into your Commonwealth account contacts group, and, if/when you delete the Commonwealth account off of your phone, all of those contacts will go with it. You may want to change this back to your iCloud account, or whatever you had set as your default contacts list previously. To do this, go to Settings>Mail, Contacts, Calendars, scroll down to the Contacts section, click Default Account, and choose which account you'd like new contacts to be added to by default.