Applies To: Microsoft Outlook 2002, 2003, 2007

Outlook data is stored in a Microsoft proprietary data file that is normally hidden from the user. As the data file is repeatedly accessed and more email, contacts, calendar events and tasks are stored, the data file grows in size. When this threshold is reached, Outlook will stop responding, email cannot be sent or received, messages cannot be moved or opened, etc.Compacting the Data Files

Follow these steps to compact any Outlook data file, typically Personal Folders or Archive Folders.

  • Mail Setup tab.
  • On the Mail Setup tab, click the Data Files button. Then highlight the data file you want to compact and click on Settings.
  • Compact Now button. This will start the compaction process which can take anywhere from a few minutes to several hours, depending upon how large and fragmented the data file is. When compacting finishes, click OK on each of the open dialog windows to return to using Outlook.