If you’ve been working with Microsoft Outlook for long, and particularly if you’re working in a Exchange Server environment (which set some pretty strict limits on file size), your Outlook .pst file may be getting too large. While you may not want to adhere to the fabled Inbox Zero standard, doing a little mail maintenance periodically will help Outlook run better. Here are five strategies for paring down your .pst file’s size.

Unless otherwise noted below, all instructions and screenshots are for Microsoft Office 2010 for Windows.

Groom your Deleted Items folder

You’re really good about deleting Inbox messages you no longer need, right? But if they’re not being removed from your Deleted Items folder, they still count toward the total Outlook file size.

You can empty the Deleted Items folder one of two ways: manually or automatically. To do this manually, right-click on your Deleted Items folder, choose Empty Folder, and they’re gone.

If you’re confident enough to say that, when you delete an e-mail, you never want to see it again, choose the automatic option. Go to the File tab and choose Options, then click Advanced. Under Outlook Start and Exit, you’ll see a checkbox next to “Empty Deleted Items folders when exiting Outlook.” Check that and click OK to save the setting.

Eliminate duplicate e-mails

Every time you forward an e-mail (particularly with attachments) to staff members, you are effectively doubling the size of storage necessary for that information, since by default a copy of that e-mail with its attachments now resides not only in your Inbox but in your Sent Items folder as well.

If there’s no longer a compelling reason to keep the forwarded version of that e-mail, go ahead and delete it out of your Sent Items folder. One trick to make this easier is to sort the e-mails in your Sent Items folder by recipient. It’s easy – just click on the To header in your Sent Items folder:

(You can simply instruct Outlook not to save forwarded messages in your Sent Items folder via a setting in the Mail/Save Messages section under Outlook Options accessible via the File tab. By default, however, any message you send, forwarded or not, is saved in the Sent Items folder.)

Save individual e-mails

Many Outlook users don’t realize they can save individual Outlook e-mails outside the Inbox in a variety of formats. Simply open the e-mail, go to the File tab, and click Save As.

You can save the e-mail as a plain text document, or you can save it in the Outlook Message format (.msg), which will preserve the formatting of the original e-mail.

Since any attachments to that message are saved in a temporary folder in Windows, it’s probably a good idea to right-click on any attachments and save them separately in the same folder on your hard drive (and make sure it’s backed up frequently).

Archive to Adobe Acrobat

If you’re ready to close a particular matter, and you got all the relevant e-mails sorted into a subfolder under your Inbox, you can use Adobe Acrobat to create an archive file that you can save your electronic records. The latest version of Adobe Acrobat include some pretty cool tools for archiving e-mail. In any version, the result is a conveniently searchable archive in a format virtually any computer can use.

Archive via Outlook

Once you’ve been using Outlook for multiple years, you may want to get into the habit of archiving your Inbox and Sent Items folders annually (or even more often if necessary).

It’s possible to automate this archiving, but since that tends to slow down the computer if you’re dealing with a large volume of e-mail, you may want to set this up manually and go to lunch. To start archiving a particular folder, go to the File tab, and under Cleanup Tools, choose Archive.

Choose the folder you want to archive (and be aware that all subfolders under that folder will be archived as well), choose the “older than” date, hit the Browse button if you want to specify a particular location and/or file name, then click OK. Depending on the volume of e-mail you’re processing, this is going to take a little while, so take a break from the computer.

Once the archive is complete, you have a separate .pst file with the older e-mails intact. If you ever need to access them again, simply go to the File tab, click Open, then choose Open Outlook Data File.

The “stitch in time” approach

If you can work some of these strategies into your regular routine, you’ll be far ahead of colleagues who suddenly can’t send or receive e-mail because their Outlook file has gotten too large. A little maintenance here and there will save you from a similar fate.

(photo: http://www.flickr.com/photos/redjar/113152393/)