Unable to open your default e-mail folders.

When setting up a new mail account in outlook to connect to an exchange server you may get one or more of these errors.

Unable to open your default e-mail folders. You must connect to your Microsoft Exchange Server computer with the current profile before you can synchronize your offline folder file.

Unable to open your default e-mail folders. The Microsoft Exchange Server computer is not available. Either there are network problems or the Microsoft Exchange Server computer is down for maintenance.

This is a generic message advising that the client PC cannot connect to the exchange server.  This could be caused by many issues, most of which are fairly easy to resolve.

Check the C drive on your server, if its full then the message store could be offline.  Try running simething like windirstat to help you clear space.  Then check the message store is online.

Go to services and start the Microsoft Exchange RPC client access. Outlook auto-discovery requires the RPC service to connect Exchange Server.

Next check is connectivity.  If you can’t ping the server then this article will not help you.

Try pinging the servers NETBIOS name from the client PC.  To find out the servers NETBIOS name right-click computer in the start menu and choose properties.  Click the computer name tab and check it in there.  This should be pingable and it should also return the server’s IP.

If the servers name is not pingable then to resolve this you need to modify the hosts file located in c:\windows\system32\drivers\etc.  You need to do this as an admin so open notepad in elevated mode and open the hosts file.  Make sure 127.0.0.1 does not have a # in front of it, if it does remove it.  Do the same with the ::1 entry, this is for IPV6 and is required by Server 2010 to be active (without a # at the front).

Add a new line with the server IP and the fully qualified server name, ie 192.168.1.1 server.mybusiness.local.  You can get the full server name from the exchange account properties in outlook.

If this doesn’t work then you can try the following.

http://support.microsoft.com/kb/913843

1. Go to Control Panel -> (View 32-bit Control Panel items, if you are on 64bit) -> Mail
2. Select the MAPI profile and click properties.
3. Click on E-mail Accounts.
4. Select the Exchange Server account and click on Change.
5. Click on More Settings.
6. Select the Security tab and check the Always prompt for logon credentials.

And also this may help http://support.microsoft.com/kb/842022