When I go to send an email from Win2PDF on Windows 2003 R2 x64 server, the MS Outlook Express wizard shows up rather than MS Outlook 2003. I've checked the Windows defaults mapi client settings, and they're set to Outlook 2003.
The problem is that Win2PDF is a 64 bit application on Windows x64, and Outlook is a 32 bit application. Windows x64 has separate default MAPI clients for 32 bit applications and 64 bit applications. Even though Outlook is set as the default MAPI client, it is only used as the default client if the calling application is also a 32 bit application. Outlook Express on Windows x64 is a 64 bit application, so the "Send PDF" option in Win2PDF chooses the default 64 bit MAPI client.
When Microsoft releases a 64 bit version of Microsoft Office and Outlook, it will work correctly with Win2PDF on Windows x64. Until then, you can configure Outlook Express to send email from other 64 bit processes. You can also install and configure the Win2PDF Font Helper application which works correctly on both 32 bit and 64 bit versions of Windows. You can download the Win2PDF Mail Helper application from the following location: