Attachments mixed up - secure temp folder 'full'???


Outlook version
Outlook 2007
Email Account
Exchange Server
We have a group of users who are heavy attachments users. They sometimes see sent e-mail messages containing wrong attachments. As example: they have doc1.xls attached to an e-mail, but when opening it AFTER sending, it's actually a .pdf document they had open and closed earlier on that day. (requires save as -> .pdf to open it)

I've read all about the securetemp folder being "full", but our users have mandatory profiles, thus starting with an empty securetemp folder every morning. They still run into the issue once every couple of weeks, even mistakenly sending docs from customer A to customer B -> not happy....

What does "full" mean in this case? I know you can have at most 100x the same filename opened, but that was not the case.

How can we prevent this issue from happening?

Windows 2003 TS

Office 2007 12.0.6514.5000