The Solution

Start the ‘Microsoft Exchange Address Book’ service on the Exchange Server (Client Access Server) which was in a stopped state.

The Issue

I received the following error message when launching Outlook in an Exchange 2010 environment.

Outlook cannot log on. Verify you are connected to the network and are using the proper server and mailbox name. The connection to Microsoft Exchange is unavailable. Outlook must be online or connected to complete this action.

OWA continued to work without issue during this time.

Why did this work? {#Why_did_this_work?}

The Address Book service performs a few key functions in Exchange 2010 including:

  • Provides information about writable domain controllers as well as global address list access.‘
  • Handles all data connections for access to Active Directory.


Background reading: