Software

DIY: Cure Outlook .pst and .ost woes

In response to a TechRepublic member question, Jack Wallen reveals a couple of troubleshooting steps he takes when Outlook is muddying the waters of the powerful .pst and .ost files.

Read my answer to an anonymous TechRepublic reader's question, and then please post additional tips for the member in the discussion.

Q: One of my client's Outlook is acting strangely and I cannot pinpoint the problem. What can be done without costing the client too much money and wasting too much of my precious time?

A: That is a great question, and one that we deal with quite a lot. Outlook is an incredibly complex application that can stump even the best of administrators. I always like to start with the simple and (almost) obvious first -- the .ost and/or the .pst file.

  • .pst: This is the file that resides on either the Exchange server or the user's local machine and keeps the user's data.
  • .ost: This is the offline file that Exchange uses to sync a user's data. This file resides on the user's local machine.

It's very important to make sure these file sizes haven't gotten out of hand. Although Microsoft states that the file size limit of a .pst file is 20 Gigs, we have found that anything above four Gigs can start causing issues.

As for the troubleshooting, what you do will depend upon what the user has. Let's assume the user's machine has an .ost file and no .pst file. If that's the case, this is what I do:

  1. Close Outlook.
  2. Locate the .ost file.
  3. Rename the .ost file.
  4. Fire up Outlook and let it re-sync.

In these types of setups, I usually find that this process does a world of good. If Outlook still has issues, it's time to look at the .pst file and take advantage of a tool that Microsoft includes with Windows called scanpst.exe. Here's what you need to do (note: this process can take quite some time):

  1. Close Outlook.
  2. Do a search for scanpst.exe and then open the containing folder.
  3. Run the scanpst.exe application.
  4. Use the tool to open the .pst file in question and scan for errors and repair them.

Hopefully, the tool will find and fix any errors in the file, and your user will have Outlook back in perfect working order.

Ask Jack: If you have a DIY question, email it to me, and I'll do my best to answer it. (Read guidelines about submitting DIY questions.)

About

Jack Wallen is an award-winning writer for TechRepublic and Linux.com. He’s an avid promoter of open source and the voice of The Android Expert. For more news about Jack Wallen, visit his website getjackd.net.

10 comments
scanpst.exe
scanpst.exe

I was perplexed when I could not open my outlook. I found this website and thanks to scanpst.exe I can get to my e-mail again. Thanks guys.

janeparker
janeparker

Hi, Backup of pst file is very essential and it is also created while using Scanpst.exe. Once you scan the PST file, Scanpst.exe shows you the errors in file. Before starting actual repair process you should mark the Make backup of scanned file before repairing checkbox to create the backup of the pst file. But it is a real fact that Scanpst.exe utility does not work for all corruption scenarios. Most of the times it fails to repair pst file. For such cases a third party pst repair tool which could recover even severely corrupted pst file should be considered. Regards Jane

windowssupportnow.com
windowssupportnow.com

I have taken PST files that were unreadable by Outlook and imported them into Exchange using the ExMerge utility and successfully cleaned up just enough to get it below 2GB. Once that's done, the user can then clean up their pst file and learn from their mistakes. I got this help from Outlook Help

jtjenkins213
jtjenkins213

I ran scanpst on an offending PST file on the VP's computer, and it ended up wiping 90% of the data that was contained within... luckily I had a backup and a backup of the backup, so I found a version that worked without errors. Beware of using scanpst, as it likes to eliminate "bad data" by erasing e-mail, contacts, attachments, or other things contained within.

chrisbedford
chrisbedford

1. When you are deleting / renaming the .OST, delete EXTEND.DAT. This is a working file which Outlook happily uses if there, even if corrupt or contining wrong information, but which it can re-create at the drop of a hat if it doesn't find it. 2. Save / rename .PST and then, from the Control Panel "Mail" applet, open Profiles and (after writing down all the relevant settings) remove the active profile. When you restart Outlook it will be as if it is being run for the first time, and prompt for all the information you wrote down. The only piece of data you won't have been able to get will have been the user's password... if that isn't available, chances are Outlook wasn't your problem in the first place! 3. Once you have gotten the user connected to his/her inbox again, it's also a good idea to import the contents of the old .PST, rather than just re-opening that file - (a) it usually creates a much more compact file, (b) could eliminate errors / corrupted mails, and (c) gives you the opportunity to keep the old PST as an archive or "restore point"

CharlieSpencer
CharlieSpencer

before it makes any changes. It's in the same directory as the original .PST.

SKDTech
SKDTech

Step 2 just made my personal Outlook usable again. Why oh why did MS not make it so outlook gives you the option to go ahead and build a new profile rather than just failing and closing if it couldn't find the file it is looking for.

Michael Jay
Michael Jay

but rather than remove the original profile use the option to prompt for profile to use and make another profile with a different name, this way if the new profile does not help you out you can quickly return to the old config. Do not rename any files, just move the non pst files to another location on the disk, they will be recreated when you reopen outlook and do a send receive all, in 2003 sometimes you have to close outlook, reopen and do another send receive all.

jtjenkins213
jtjenkins213

True, it does make a backup. But I used my backup as I knew it was a working PST. I just used the utility in an attempt to save e-mail from later than the last backup (which was about 72 hours old, the backup routine worked on a Friday and I ran the utility on a Monday... no idea why I remember that considering it was over three years ago). I just thought it a good idea to state that scanpst is not to be used lightly considering the article's suggestion and its lack of warning on what scanpst could do to the data contained within a PST. This of course isn't meant as nonconstructive criticism... Any utility that may modify something such as a PST file should be run with caution. I mean no offense to the author as it is a good utility to use.

Michael Jay
Michael Jay

so you can choose to not make a .bak file if you want to, I choose to not make the .bak file as I have already backed it up. Guess it does not matter as backing it up first will end up costing you as much time as letting scanpst do it.