What is the default refresh rate for Autodiscover

Here is all of the details on how Autodiscover can refresh it's cache. An Outlook 2007 client automatically contacts the Autodiscover service:

  • Each time it boots
  • At intervals on a background thread
  • Whenever the connection to an Exchange server fails
  • There are two parts of Outlook that use Autodiscover.
  1. The Outlook layer
  2. The MAPI layer.

The Outlook layer runs at every boot to get settings, and refreshes them as often as the TTL period specifies (60 minutes), or when there’s an error contacting one of the servers, whichever comes first. If we fail to get Autodiscover information, the Outlook layer will retry every 5 minutes because the settings aren’t persisted through restarts, so booting up without Autodiscover means you don’t know where to go for free/busy, OOF, OAB or UM until we get those settings.

The MAPI layer only runs Autodiscover when there are errors connecting to the server MAPI is trying to connect to. For instance, trying to open your mailbox after a mailbox move, or trying to open someone else’s mailbox when it’s in a different forest (yes, we support Cross-Forest access this release, if you have trusts established between the two forests). We also will perform a “free” Autodiscover every 6 hours on the MAPI layer if there are network errors such as not having RPC/HTTP settings, going home and trying to connect using RPC/TCP and failing with a network error – in this case, the user wants their settings refreshed just in case the RPC/HTTP server has changed.

We also run Autodiscover at profile creation time to configure all the server settings stored in the MAPI profile, but web service information used by the Outlook layer is not persisted to the MAPI profile.

If you are connected and your mailbox is moved, Outlook detects this and uses the new information the next time it tries to connect.

I want to thank Ross Smith for getting the updates on this.