Outlook 2007 Maximum Size Error - how to fix?



I am using Outlook 2007 on a Vista Home Premium Machine.

Tonight I received an error message in Outlook stating the following:
"The file C:\users\username\AppData\Local\Microsoft\Outlook\Outlook.pst has
reached its maximum size. To reduce the amount of data in this file, select
some items that you no longer need, then permanently (shift + del) delete

The file is just over 20GB, which (surprise) I just learned is the max pst
file size.

The problem: Outlook will not let me delete anything from the file. No
matter what I try to shift+del or move to a different PST file, I get that
same message.

I am unable to send/receive any messages at all and cannot find a solution.
I searched in the MS KB and found KB article 832925 "How to configure the
size limit for both (.pst) and (.ost) files in Outlook 2007 and in Outlook
2003", but I am not a registry editing-expert and the keys that it suggests I
fix, supposedly located in
HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Outlook\PST, are
not on my machine. I do not have any OFFICE keys in the
HKEY_CURRENT_USER\Software\Policies\Microsott registry.

Any suggestions on how to fix AND save my e-mails?



You save your data by merely copying the data files, with outlook closed to
another location, or by using your backup software - you do have such dont

Roady [MVP]

You'll have to create the keys in case they don't exist.
You also might want to see this;

It would be wise that after you have modified those registry keys, you
clean-up the pst-file that it falls below the 20GB threshold. Depending on
its size afterwards, you might want to start with a clean pst-file via;
File-> New->Outlook Data File...

After that, remove the registry keys again. It is not that the 20GB is an
absolute limit (that one lies much higher) but currently the hardware can be
the limiting factor to keep up performance when a pst-file goes beyond the
10GB limit. Also, regarding backups there might be a practical concern.

That said, reaching the 20GB threshold is quite an achievement. I curious
how you performance is/was both before Service Pack 2 and after. Also, I
hope you made regular backups and checked them as 20GB is a lot of data to


Alright, DL, thanks for the sarcasm. Always useful. The issue *was* that I
couldn't DO anything with the data, not that I don't know how to back-up &
restore. Outlook was blocking allcopying, pasting, deleting, etc. due to the
size of the file.

Roady, though, was very helpful! I added/edited the registry keys to
increase the max file size, which allowed me into the .pst again so that I
could do the deleting & scrubbing necessary. Astoundingly enough, there were
e-mails in sub-sub-folders dating back 14+ years, so no surprise that the
file eventually grew massive.

SP2 has not yet installed; waiting in the queue & will probably run it

Roady [MVP]

You're welcome! :)

After applying SP2, the recommended maximum size of your pst-file on good
hardware is up to 10GB. On average hardware it is 5GB.
This doesn't mean that you can't make it larger but just that performance
might degrade after that or that you could experience pauses. Whether or not
you find that acceptable is up to you of course :)


You know all about backups, but then go on to say you could'nt do anything
with the data within OL , you DONT backup OL data within OL or even if OL is

Roady [MVP]

DL, I think you've missed the issue here. The question was never about
backing up but about unlocking the oversized data file without losing data
and getting Outlook operational again. Your suggestion would not have
achieved that.


Yup, that's it. Even if I restored my backup copy of the PST file, it was so
large that Outlook wouldn't let me make changes to the contents. So
restoring the backup would have put me right back where I already was, unable
to manipulate the files.


Do these file size limits still apply to Outlook 2007?
Does anything change if using BCM?
Thanks in advance.

Diane Poremsky [MVP]

if you use the Unicode pst format, you can edit the registry to create
larger pst files. BCM is a database for contacts - it does not have the
same limits as a pst.


You can try a popular Outlook recovery tool called Advanced Outlook
Repair to repair your PST file. It is a powerful tool to recover
messages, folders and other objects from corrupt or damaged Microsoft
Outlook PST files.

Detailed information about Advanced Outlook Repair can be found at

And you can also download a free demo version at http://www.datanumen.com/aor/aor.exe
Good luck!


Roady [MVP] I just upgraded from Office 2000 to 2007 and I'm having the same
issue. When I reach the link you posted to create the keys there is a note
that says it does not apply to files created in 97 - 02. Would I be able to
do the same location in the registry except go to 9.0? If not what process
should I follow?


Outlook is featured with an inbox Repair Tool (scanpst.exe) which only helps to fix or repair minor errors and corrupted pst files not made for split over sized pst files.


Outlook 2007 default size limit is 20 GB. You cannot cross at that time your PST may be corrupted. You can do one thing, Download and install free edition of PCVITA Recover Outlook and launch the program. Select your PST file.. Software start scanning and recovering PST file and show a preview for recovered data. You can also cut large PST file and save into more than 1 smaller files using split option.
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