I am trying to understand why we have an ISP that houses our external mailboxes for us, and for internal mailboxes, I need to set them up on our Exchange Server here in-house.
Could both our external and internal mailboxes be set up on ExchangeServer here in-house, or must external mailboxes reside with ISP?
If there is a reason why this might have been set up this way, and if so, could some one please explain this to me?
Thank you in advance.
