It is safest to create a dedicated mailbox for Epicenter Server. Epicenter will have direct access to many (or all) mailboxes on your Exchange Server. If you were to use your personal mailbox for Epicenter, then anyone walking up to your computer could open any mailbox used by Epicenter without a password. Worse, if your laptop were stolen, the thief may also be able to access those Exchange accounts.
Dedicated Exchange environments
If you are on a domain with a dedicated Exchange Server, you'll need to create a new account for Epicenter and create a mailbox. Do not reuse any of the Administrator accounts because they are specifically denied the required rights.
Hosted Exchange environments
If you use Hosted Exchange, creating a dedicated mailbox for Epicenter is strongly recommended to prevent security holes, as described above. The procedure for doing this will depend on your hosting provider.