ActiveSync and Your iPhone
Once your device successfully connects to the Exchange server, you can choose to synchronize mail, contacts, calendar items, or any combination of the three. This allows you to select what you want to synchronize, and save battery power by not synchronizing the things you may not need or want.
When you're using Microsoft ActiveSync, email that you've read on your device will be marked read in Outlook as well, and vice versa. Drafts saved on your iPhone will also be found in the drafts folder in Outlook.
Another benefit to having Microsoft Exchange available to sync your iPhone with, is the ability to disable or even wipe the device remotely. Anyone who has ever owned a cell phone has misplaced it a time or two. Cell phones are frequently left on public transportation, in hotel rooms, on restaurant tables, dropped on the street, etc.
Even if you're not a very high-ranking person within your firm, or your data is not sensitive, someone with access to your device could still cause problems for your company including legal issues. This could not only put your company at risk, but your personal contacts as well. Anyone in your contact list could then become a target for harassment or even virus laden emails.
If your company uses Microsoft Exchange, you would be able to get into your email account, you could prevent this with the simple click of a button.