Collaboration data objects for Windows NT, for Windows 2000, and for Exchange 2000 require Outlook Express

Collaboration Data Objects (CDO) for Windows NT (CDONTS), CDO for Windows 2000 (CDOSYS), and CDO for Exchange 2000 (CDOEX) require that you have Outlook Express installed on your computer. If Outlook Express is not installed, or if some components are corrupted, you receive random errors. You may receive the following errors: This issue also occurs with System.Web.Mail. System.Web.Mail is a wrapper for CDOSYS and CDOEX.

This problem occurs because CDONTS, CDOSYS, and CDOEX use Outlook Express DLLs to load the configuration information.

To resolve this problem, follow these steps:

1. Install Outlook Express if it is not already installed. To do this, follow these steps:
   1. From Control Panel, click Add or Remove Programs.
   2. Click Internet Explorer, and then click to select Outlook Express as the component to be installed.
2. If Outlook Express is already installed on your computer, and you receive one of the errors mentioned in the "Symptoms" section of this article, follow these steps:
   1. Remove Internet Explorer from your computer.
      
      This also removes Outlook Express.
   2. Reinstall Internet Explorer. During installation, select to install Outlook Express.
3. If you receive the errors mentioned in the "Symptoms" section of this article after you install or reinstall Internet Explorer and Outlook Express, follow these steps:
   • On a computer that is running Windows 2000, run the following commands at a command prompt to register Cdonts.dll and Cdosys.dll:
     
     regsvr32 "\WINNT\System32\CDONTS.dll" regsvr32 "\WINNT\System32\CDOSYS.dll"
   • On a computer that is running Windows NT with the Windows NT Option Pack (NTOP) installed, run the following command at a command prompt to register Cdonts.dll:
     
     regsvr32 "\WINNT\System32\CDONTS.dll"
   • On a computer that is running Windows XP or Windows Server 2003, run the following command at a command prompt to register Cdosys.dll:
     
     regsvr32 "\WINDOWS\System32\CDOSYS.dll"
   • On a computer that is running Microsoft Exchange 2000 Server, Exchange Server 2003 , Microsoft Sharepoint Portal Server, or Microsoft Sharepoint Team Services, run the following command at a command prompt to register Cdoex.dll:
     
     regsvr32 "\Program Files\Common Files\Microsoft Shared\CDO\CDOEX.dll"

This behavior is by design.

The errors mentioned in the "Symptoms" section of this article occur at the CreateObject line in the code. For CDONTS, the error occurs at CreateObject("CDONTS.NewMail"). For CDOSYS and CDOEX, the error occurs at CreateObject("CDO.Message"). These errors are returned if the code is run in ASP, run as a script, or run as an application.

Note If Outlook Express is installed on your computer and corrupted components cause the error, reregister CDONTS.DLL to resolve the problem. However, you typically must reinstall Outlook Express. Also, if you reinstall Outlook Express, the problem may resolve. If so, you do not have to register CDONTS.DLL.

For more information, visit the following Microsoft Web sites: