OAB Improvements in Exchange 2013 Cumulative Update 5

By Ross Smith IV,

Dedicated OAB Generation Mailboxes in Cumulative Update 5

CU5 moves away from the previous model where an OAB generation mailbox generates all the OAB's in the organization. While an OAB generation mailbox can continue to generate multiple OABs (the default behavior when you deploy Exchange 2013), what's new in CU5 is that an OAB can only be assigned to a single OAB generation mailbox.

This architectural change addresses the aforementioned deficiencies:

  • By allowing administrators to define where an OAB is generated.
  • By removing the capability to have multiple instances of the same OAB, mitigating the scenario where a client could hit a different OAB instance triggering a full OAB download.

From a connectivity perspective, Autodiscover provides back an OAB URL for the site in which the user's mailbox is located. That URL resolves to a Client Access server which proxies the request to the linked OAB generation mailbox that is responsible for generating the requested OAB.

As a result, Contoso can now display the following OAB architecture:

Redmond users will now only download the Redmond OAB from the Redmond AD site and Portland users will only download the Portland OAB from the Portland AD site. Neither set of users will have an OAB full download as a result of traveling between locations because the users will always be referred back to the Mailbox server hosting the OAB generation mailbox that contains their OAB.

To read the full article, go to: The Exchange Team Blog

Use Ctrl+Shift+R to "Reply all" to the selected message.


Will tablet and Smart phone use be a big part of your OWA 2013 deployment?