Microsoft Outlook has multiple ways it saves information as you work. Every time you send an email, the address is cached and all of your emails and files are automatically archived to a .pst file on your computer. Over time, having all this stored information can slow you down, but fortunately, there's an easy way to clean it. To delete Outlook cache file, you'll need to find its location under settings and manually delete it, while you'll clear your email address cache in Outlook settings.
Cleaning the Outlook Cache
As a protective measure, Microsoft automatically archives your emails to a location on your computer, which you'll need to make sure is included in your backups if you want to protect them. Messages from your inbox, as well as drafts, are automatically sent to autoarchive after six months. Sent and deleted items are archived after two months and outbox items are archived after three months. Your calendar, tasks, notes and journal are archived after six months.
You may find your archived files are taking up space on your computer, which can be a problem if you send and receive a high volume of emails each week. You can delete this file, but first you'll need to find your Outlook cache file location. To find the location of your autoarchive folder, go to File, Options, Advanced and Autoarchive Settings. Halfway down, you'll see Move Old Items To, and the address of your autoarchive files will be there.
On the same screen as your Outlook cache file location, you'll also be able to adjust your autoarchive settings. You can change how often autoarchive runs and even set it to prompt you before autoarchive starts its work. Here is where you can also permanently delete old items instead of archiving them if you'd prefer to keep your hard drive clean. If you choose this option, though, be aware you'll lose all old emails after the chosen timeframe.
Clear the Autocomplete Cache
Sometimes you're looking into how to delete Outlook cache file because you're tired of typing the first couple of letters of a new colleague's name, only to have an old frenemy pop up. To eliminate a name from that cache, start typing it and select the X next to the name you want to remove. If there's more than one name, press the down arrow until you reach the name to be deleted.
In some cases, there are simply too many names to remove. You can remove all the names from the Outlook cache file location by selecting the File tab, then selecting Options. Select the Mail tab and the button Empty Autocomplete List. You'll be asked to confirm you want to delete the autocomplete list before the request is finalized.
Disable Outlook Autocomplete
If you want to prevent autocomplete from kicking in moving forward, you can easily disable Outlook autocomplete for Outlook 2010, 2013 and 2016. Go to File and Options, then select the Mail tab. About halfway down the page, you'll see Send Messages. Beneath that, uncheck the box next to Use Autocomplete List to Suggest Names When Typing in the To, CC and BCC lines.
Outlook 2003 and 2007 put the disable Outlook autocomplete feature under Tools, Options and Email Options. Click Advanced Email Options and uncheck the Suggest Names While Completing To, CC and BCC fields. If you ever change your mind and want autocomplete to return, simply follow these directions to check the Suggest Names box.