How to maintain Outlook data (PST) Files

By: standss , May 24th, 2010

If you have been using the same Outlook data file for a long time, then you may need to check it’s size and do some maintenance… or you could suddenly (i.e. without warning) end up with a corrupted Outlook data file with Outlook no longer able to open your emails.


If you started using (or maybe are still using) Outlook before Outlook 2003 then your PST file (Outlook data file) is allowed a maximum size of 2 GB. This may still be true even if you migrated to new versions of Outlook since then.

Data files created by Outlook 2003 or later have a much safer limit of 20 GB. But…if you migrated from an older version of Outlook, then chances are your Outlook data file is still in the old format.

If your pre-Outlook 2003 data file exceeds 2 GB then Outlook will not be able to open it… there’s also no warning built in to Outlook telling you that you are getting close to this dangerous limit.

What version is your Outlook Data file?

If you are using Outlook 97, 2000 or 2002/XP then you are using the old format with the 2 GB limit.

If you are using Outlook 2003, 2007 or 2010, use the following steps to find out what version data file you currently have.

  1. Inside Outlook, right-click over the top folder and click Properties.
  2. Click the Advanced button

If the format displayed says Outlook Data File(97-2002) then you are using the old format. If it says Outlook data File then you’re using the new format.

Things you can do to keep your data file small

  1. Delete messages that you don’t need to keep (don’t forget the Sent Items folder)
  2. Empty the Deleted Items folder regularly.
  3. Compact your PST file occasionally to remove the empty space that remains even after you delete emails. (Click the Compact button shown in the screen above)

I hope these few guidelines will help you keep your Outlook data safe.

3 Replies to “How to maintain Outlook data (PST) Files”

  1. Thanks for the info. I have Outlook 2003 on Windows 2000(!), no idea what tired version of Exchange we use.

    About half of mine show up as “Personal Folders File (97-2002)”. The rest are “Personal Folders File”.

    I assume that that these are just alternative names for ‘Outlook Data File’, but why?

  2. Not sure how to carry out the Compact command in Outlook 2007 – can’t find the “Properties” command.


    Miles Barry

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