Should I compress old email messages in Outlook Express?

Q  I have a Windows XP PC and use Outlook Express for my email. Each time I launch this application, Windows displays a warning that I should compress old messages. When this appears, I click Cancel.

However, recently it has begun popping up all the while and I cannot seem to silence it for long – and it’s really beginning to annoy me. What is it and how can I stop it?
Terry Dowers

A  This warning is set to trigger automatically each time Outlook Express is opened after the first 100 times it has been launched. Essentially, the application is asking for permission to reduce the size of its message database.

It does this by removing (or ‘compacting’) the space left between remaining messages when unwanted emails are deleted. Besides freeing up some disk space, this may lead to a small performance boost, as Outlook Express won’t have to work quite so hard to sort through your inbox.

Though it can take a good few minutes to finish the job, compacting Outlook Express’ database every now and then is a good idea. Giving the program the permission to go ahead should also suppress the message, at least for the next 100 launches. In between times, the process can be launched manually. To do this, open the File menu, point to Folder and click Compact All Folders.

While this should remove your annoyance, there is a known bug that can lead to this warning message continuing to appear even after compaction has taken place. Fixing this isn’t difficult but does involve editing the Registry, so proceed with caution.

Click Start followed by Run, type regedit into the box and press Enter. Now create a backup of the existing Registry by opening the File menu and choosing Export (type in a file name for the backup and then click Save).

Now click the plus (‘+’) symbols in the left-hand pane to navigate to HKEY_CURRENT_USER\Identities\[LONG-UNIQUE-NUMBER]\Software\Microsoft\Outlook Express\5.0 (where [LONG-UNIQUE-NUMBER] will be a long number unique to your Windows user account).

In the right-hand pane, look for an entry labelled ‘Compact Check Count’ – this will have a value of 100 (or more). Right-click this entry and choose Modify from the pop-up menu. Type 0 (zero) into the Value data field and click OK. Close the Registry and restart Outlook Express.