If your organization has Outlook Web Access enabled, meaning you can check your email with a browser from any where you have an internet connection, then:
You can Google add exchange account to blackberry and get tons of info if that above is not enough.
PS This is how we have ours setup and it works pretty much flawlessly…pretty much.
Her other option is to sync by the cradle using the desktop software while in the office only. Then when she takes it out of the cradle and leaves the office she will no longer receive email to the device.