Windows XP-based clients do not receive "new mail" notification messages after you install Service Pack 1

After you install Service Pack 1 (SP1) for Windows XP Professional, you may no longer receive Outlook "new mail" notifications when you receive e-mail messages. Also, when you start Outlook to the Inbox folder, you must click another message or folder before new messages appear in the Inbox.

This issue may occur if all the following conditions exist:

• The Windows XP Professional-based client computer is behind a Microsoft Internet Security and Acceleration (ISA) Server 2000-based firewall.
• The Windows XP Professional-based client computer is configured to use the Microsoft Firewall Client program.
• The Local Domain Table (LDT) on the ISA Server 2000 computer does not contain an entry for computers in the local domain.

This issue occurs because the Information Store process (Store.exe) on the Microsoft Exchange server sends a User Datagram Protocol (UDP) packet for new mail notifications. However, because this UDP packet depends on name resolution for correct delivery, if the LDT on the ISA Server 2000 does not contain an entry for the computers in the local domain, the Exchange server cannot deliver the UDP "mail notification" packet. In this case, the client responds with a "Destination Unreachable" ICMP packet when the server sends the UDP packet. This issue occurs although the Windows XP client computer is communicating with an internal Exchange server.

To resolve this issue, create an entry in the LDT of the ISA Server 2000 computer for the internal Active Directory domain:

1. Start the ISA Management utility. To do this, click Start, point to Programs, point to Microsoft ISA Server, and then click ISA Management.
2. Expand Servers and Arrays, expand your server or array, expand Network Configuration, and then click Local Domain Table (LDT).
3. Right-click Local Domain Table (LDT), point to New, and then click LDT Entry.
4. In the Name box, type the fully qualified domain name of the computers that you want ISA Server 2000 to consider as members of the local domain. You can use the asterisk (*) character as a wildcard character. For example, if your domain is named example.com and you want all computers to be considered as members of the local domain, type *.example.com. If you want to specify a single computer, type the fully qualified domain name of that computer. For example, computer1.example.com.
5. Click OK.
6. When you are finished adding entries to the Local Domain Table, quit the ISA Management utility.
7. Restart the ISA Server 2000-related services.
8. On the client computers right-click the Microsoft Firewall Client icon in the notification area, and then click Configure.
9. Click Update Now, click OK, and then click OK.
10. Quit and then restart Outlook if it is running.

For more information about related topics, click the following article numbers to view the articles in the Microsoft Knowledge Base:

For information about how to obtain Service Pack 1 (SP1) for ISA Server 2000, visit the following Microsoft Web site:For additional help and support with ISA Server 2000, visit the following Microsoft Web sites: