Hi Ross,
Thank you for clarifying the MSFT best practice regarding size limits. We were recently contacted for our "secure file transfer appliance" products by a VAR who focuses on Exchange/Outlook implementations and because of the Exchange 2003 (default) limit; they need a complimentary solution that would still allow users to send large files.
The reality is that large attachment/file is common in most business processes today. The "tricky" part of email attachment is that users like to CC and BCC a lot of people but at the same time, unless you work at the few industries where there are specific retention regulations, the "shelve life" for most of these attachments are rather short. So, sending these data as email attachment impacts both the network performance and storage requirements. On the other hand, if you can do an "attachment offload" that is transparent to the end users, suddenly everyone is happy - end users gets to send the files/emails they need and IT does not have to worry about email infrastructure being under siege.
Regards, YFJ