U2U forum member Steven B Sutherland has created a small Borland Delphi program that calls the default Email program and passes the exported photos to it. This works around issues with email clients that refuse attachments passed to it (eg Outlook Express).
In his readme Steven notes
“This program addresses the problem of not being able to create an email, with selected photos attached directly out of Lightroom in Windows.
It is a simple program which will accept a list of files on the command line and then it uses the MAPI API to invoke the systems default email program. It opens a new email with all of the passed files attached. Once the email is sent (or cancelled), the passed temporary images are deleted automatically”
The program can found on Lightroom Extra, in the Download/Other Goodies section.