When emails are sorted on arrival into folders by Outlook 2007 rules, they do not appear on a BlackBerry. If, using Outlook, the emails are moved manually into subfolders, the messages do appear on the BlackBerry.
The solution is to have the user (or you signing in as the user) surf to the BlackBerry WebDesktop which you can usually find at https://YourBesServersHostName:3443/webdesktop . Click the EMAIL SETTINGS tab, then the REDIRECTION FOLDERS menu item (on the left), then expand your INBOX and check on what see what you can see on your Blackberry:
Note that this only works if your mail is stored on your Exchange (or Lotus Notes I suppose) server. If you are using POP3 and PST files, you are toast. The only work around I have found for that configuration is to create rules on the server rather than in Outlook, but that is an ugly complex solution.
Single Server BES 5 Express
Single Server Exchange 2007 SP2 (with all Hot Fixes but not SP3 because SP3 does nothing useful for this company)
BBerry Bold 9700
On Telus Network
Outlook 2007 SP2 with all current patches
Mail goes to OST files locally, not PST files