If you use Outlook 2003 and custom forms you've probably discovered the hard way that it has a problem with a corrupt forms cache. The recommended solution is a batch file to delete the cache. A hotfix is available to fix the forms cache corruption in Public Folder Favorites (and other issues); as usual you'll need to call PPS to get it. (We're waiting on a fix for other forms cache issues.)
For more information see Outlook 2003 Hotfix Package: January 20, 2004 and 831586 Problems Occur When You Open a Custom Form by Using the Favorites Folder
The following previously undocumented issues are also fixed in this hotfix package:
If you create an address book entry for an e-mail contact that does not automatically resolve, a badly formatted search key may be created.
When you programmatically enumerate your Inbox using the MAPI MapiReadMail function, the szMsgId parameter may be returned. However, the szMsgId parameter cannot be used by the MAPI MapiReadMail function.
If your network or your Internet connection is disconnected while Microsoft Outlook is sending e-mail messages, those e-mail messages are not actually sent even though they appear to be sent and have been moved to the Sent Items folder.
Published February 24, 2004. Last updated on October 1, 2014.