Windows Explored

Every now and then someone would complain about this message appearing after logon: “To free up disk space, Outlook Express can compact messages…”

The problem was that they failed to complain to the right person. Eventually, one of my co-workers encountered it and asked me to investigate. We thought it odd because we used Outlook, not Outlook Express. To quickly identify the culprit, I turned to Process Explorer from SysInternals and used the Find Window’s Process menu icon. Simply drag the crosshairs over the window in question and Process Explorer highlights the process. You can see below the process identified was WindowsSearch.exe:

Unknowingly, perhaps during a user initiated Windows update, Windows Search 4.0 service was installed. A quick search on the Internet shows that after installing this search service it causes a reg value to increment by 1 each time a certain value is queried. The value in question is a DWORD named Compact Check Count in HKCU\Identities\{identity}\Software\Microsoft\Outlook Express\5.0. After reaching 100, it causes the above message to be thrown after logon or whenever an eml file (Outlook Express message) is opened.

This can be eliminated by uninstalling Windows Search. Alternatively, this can be worked around … to some degree. Windows Search offers an option to disable the indexing of Outlook Express items. To do this, right-click the Windows Search icon in the system tray to change the Indexing Options and then select Modify:


Next, uncheck the box(es) for Outlook Express.

Aftrwards, reset Compact Check Count DWORD to 0.

Note, that each user logon will increase this value by 1 as long as the search service is installed as will opening any eml message with Outlook Express (regardless of whether Windows Search is installed). In the latter case, I suppose you can change the .eml file extension to be opened by Outlook instead to avoid this. As for the logon tick count going up when opening any eml message with Outlook Express, setting read only permissions on the key where the value resides may do the trick, but I haven’t tested to see what impact this may have, if any, on other components. In this case, my co-worker didn’t need Windows Search so I uninstalled it, eliminating the problem.