Microsoft Office Tutorials and References
In Depth Information
An Exchange hybrid environment has the following requirements:
● You must always have an on-premises Exchange server to facilitate the hybrid model.
● You must install an Exchange 2010 SP3 Client Access Server (CAS) role in your
Exchange 2003 or 2010 environment, or if you already have Exchange 2010, you
must install Service Pack 3 (SP3). CAS will serve as the bridge between your on-prem-
ises Exchange and Exchange Online.
Why Exchange 2010 SP3?
Exchange 2010 SP3 was released on February 2, 2013 and can be downloaded at http://
www.microsoft.com/en-us/download/details.aspx?id=36768 . Prior to the latest release of
Office 365, only Exchange 2010 SP2 was required. SP3 facilitates hybrid models
involving the latest version of Office 365, which features Exchange 2013 technologies.
● Directory synchronization should already be installed and configured for Active
Directory write-back. This was covered in Chapter 4, “Directory synchronization”.
Refer to Figure 4-35 in Chapter 4.
● Access to a Domain Name System (DNS) for your domain to create the necessary
DNS Autodiscover and service (SRV) records. If you want to route email through
Office 365 instead of your on-premises Exchange Hub Transport server, you will
need to modify your organization’s MX records. We will create and modify DNS
records shortly, so make sure you have the ability to make DNS changes for your
● If you are planning a phased migration, identify which mailboxes will move to
Exchange Online and which ones will remain on-premises.
As you plan the placement of mailboxes, take special note of which mailboxes have
delegate permissions. Delegate permissions, such as delegate access, folder permissions,
and “send on behalf of” are not available unless the delegates coexist with the mailbox.
Therefore, if a manager has an assistant with delegated rights to the manager’s mailbox,
you should plan on having both the manager’s mailbox and the assistant’s mailbox reside
on-premises or in Office 365. Do not separate these two individuals’ mailboxes.