thanks for the replies. I will confirm whether attachments are being
written to the secure temp folder when they are being previewed
shortly.

"Attachments (including embedded images) are downloaded to the local
system when you preview messages - they get written to the securetemp
folder when you select the message for preview and are scanned by the
AV."

Any way to turn this off? In my situation, with a hosted remote
Exchange server, it makes using the additional mailbox almost useless,
as Outlook hangs whenever a large message is previewed (obviosuly
until the attachment has finished downloading). Pretty frustrating. I
have many employees who share this additional mailbox - this issue was
unnoticeable with a local Exchange Server.

I am sure that Outlook 2003 behaved differently (well, I really need
to test this to confirm)

This article : http://www.slipstick.com/outlook/securetemp.htm seems
to imply that the data is written to secure temp when the attachment
is opened, rather than the message just being previewed?