The Exchange server address list service failed to respond. This could be because of an address list or email address policy configuration error.

If it is a problem with the Microsoft Exchange System Attendant Service then you need to restart it by:

• Typing services.msc in the run box
• Then find the Microsoft Exchange System Attendant service
• Select Restart

Check where the default public folder database is by:

• Go to Organization Configuration > Mailbox.
• Select the mailbox database that you want to change the default public folder database.
• Right click the database and select properties
• In <Mailbox Database Name> Properties, click the Client Settings tab.
• Next to the Default public folder database box, click Browse.
• In Select Public Folder Database, select the public folder database from the list of public folder databases, and then click OK.