It’s Not Enough to Just Delete Old Messages in Outlook, You’ve Got to Compact

Q: My Outlook has been running really slow, and I finally figured it’s probably because my Inbox and Deleted Items files are huge. I’m embarrassed to say that I’ve accumulated several years of e-mails. So I recently spent an hour or so of quality time deleting messages. But now, after all that effort, I find my pst file, which holds all of Outlook’s data, is still about as large as it was before I did those deletes, and my e-mail is still sluggish. To make matters worse, when I delete a whole bunch at a time, my system keeps hanging up with an Out of memory error. Can you help me get out of this mess?

A: Let’s tackle one problem at a time. You’re discovering that it’s not enough to just delete old messages. You’ve got to take one more step: defrag the .pst data files, which in Outlook’s lingo is called Compacting.

To compact a .pst file in Outlook 2003, click on File, then on Data File Management and Settings and finally on Compact Now (see screenshot atop the next column). The defragging will probably take a few minutes—depending on the size and degree of fragmentation of the file. When it’s done, click on OK.

For Outlook 2007, click on File, Data File Management, which opens the Account Settings dialog box. Go to the Data Files tab and click on Settings and finally on Compact Now.

Now, let’s tackle why your system hangs up when you try to delete a large number of e-mails. I would bet you’re connected to Exchange Server, and Outlook is trying its best to communicate with the server for every deletion, but its getting overwhelmed. So, when you’re ready to do a major deletion, first disconnect from the server. Then, after the wholesale deletion is finished, reconnect and your computer will sync with the server in the background.

Finally, let’s get to the heart of the matter: You’re doing a poor job of e-mail housekeeping. Here is what you should be doing to keep Outlook running smoothly.

First, don’t let your Inbox balloon. Move messages to Deleted Items when you’re reasonably sure you don’t need them. Also, if you need a place to temporarily store certain messages, use the color flags to code their priorities. Better yet, consider creating subfolders under your Inbox by right-clicking on that icon and creating a new folder with a distinct name. Every month or so, scan what’s in Deleted Items and clean out those you really don’t need. Do the same with the Junk E-mail folder and delete those that got through the filter.

Tip: If you want to completely delete an e-mail, don’t just click on Delete or it will go into the Deleted Items folder. Instead, erase it with Shift+Delete.