Why you use the New Message feature in Internet Explorer, or click a mailto link, or use the Send To feature of a program, Outlook Express is not used?
The problem can occur if the default mail client entry is missing in the registry or if Outlook Express is NOT you default mail client.
To fix the problem, first try to register Outlook Express as your default mail client:
1. Press Start.
2. Press Run.
3. Type "<drive:>\program files\outlook express\msimn.exe" /reg where <drive:> is the the drive letter that Outlook Express is installed on.
4. Press OK.
Try clicking an email link. If outlook Express is still NOT used:
1. Use the registry editor to navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Clients\Mail\Outlook Express.
2. The (Default) or <NO Name> Value Name should be a string (REG_SZ) data type and the data value should be Outlook Express.
3. The DLLPath value name should be a REG_EXPAND_SZ data type and the data value should be the full path to the Msoe.dll file,
<Drive:>\PROGRAM FILES\OUTLOOK EXPRESS\MSOE.DLL or %ProgramFiles%\Outlook Express\msoe.dll.