I have outlook 2007. There's a PST file that Outlook is now refusing to open. When I click on it, it says

The set of folders cannot be opened. XXXXX.pst has reached its maximum size...

Outlook is telling me to delete items from the PST. But... ah... the folder is not openable, so of course I cannot delete items.

I read up a little on this. The older Outlook datafile format supported a max size of 2gb. This file is right around 2gb - just under. And I checked, it is a Outlook 2000-2002 PST file.

How can I solve this problem?


I looked around and found many many different websites that offer 1-off tools for purchase that purport to solve this problem. Mostly the websites are written in poor English and the prices are around $49. With so many shady tools trying to monetize this problem, I figured there would be a simpler solution.

  • the first option I considered was the scanpst.exe tool, included with outlook. I ran this on the file, and it actually increased in size, slightly. Trying to open the "fixed" file in outlook gave me the same error.

  • The next option I considered was the PST Crop tool, from Microsoft. The tool, I gather, simply truncates the PST file, and then re-indexes it. You lose "some amount" of data from the PST file. This sounded really undesirable to me, so I rejected this idea.

  • The next option I considered was manually modifying the PST file myself, according to the general outline described here. But this started to look pretty complicated. I could easily copy the pst file, and introduce a corruption, then run scanpst, and get the resulting "smaller" pst file. And the suggestion is to do that more than once, introducing artificial corruption into the original PST file in different places, thereby recovering all of the data in the file. But the problem is I'd have duplicates, and I'd need to resolve all those duplicates afterwards. Something I didn't look forward to. so I rejected this too.

  • I looked into PST Walker, a $49 tool that opens PST files without relying on Outlook or the Outlook automation. There's a trial version of the tool, which I used to read the PST file. This showed that the file was not corrupted. but the tool is a read-only thing, and I didn't see a way to export the data into a smaller PST. So I ruled this out.

  • finally - the solution. I just compacted the PST file from within outlook. It resulted in a savings of about 300mb in the 2gb file. Compaction took about 30 minutes.

Like this:

1.On the File menu, click Data File Management.
2.Click to select your Personal Folder, and then click Settings.
3.On the General tab, click Compact Now.
4.Click OK, and then click Close.

After compaction, I was able to open the file within outlook. At this point I will convert the PST to a Unicode (Outlook 2003) PST file, which is not limited to 2gb.

I hope this helps someone else.

I think it's shameful that outlook can allow you into the situation where you add an item into a PST, and that makes the PST unusable within outlook. But there is a reasonable solution - compaction and conversion - that may allow you to avoid the problem in the future.

  • A prevenative solution is to archive some of the data into another PST once a year or whenever space is needed. Nice post. – Moab Sep 27 '11 at 4:29
  • Just to be sure, you aren't running Outlook / Windows cache or storing PST file on a storage device that uses FAT filesystem? – laika Oct 25 '12 at 15:01

This worked perfectly for me:

  1. On the File menu, click Data File Management.

  2. Click to select your Personal Folder, and then click Settings.

  3. On the General tab, click Compact Now.

  4. Click OK, and then click Close.

You may want to delete or move large items out of the PST file and repeat the compaction process too.

  • Hello Pedro, and welcome to SU.SE - the linga franca of the site is English, so I'm not sure how your Spanish will be taken... – Andrew Oct 25 '12 at 15:03
  • Translated it to English. – Renan Oct 25 '12 at 15:24

I use the tools provided from SplitPST to split the files, thus preventing those issues:

You can use split PST software to split PST file outlook 2007 into smaller files. This software ensures that no data is lost while splitting your PST file.

User guide here.

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