Showing results for 
Search instead for 
Did you mean: 
Level 6
Partner Accredited Certified

In this article I'll give you five reasons you should eliminate PST files from your environment. These aren't the only five, and some might not be applicable to your usage of PST files. However the list should stir the murky waters of your mind and get you thinking of your five reasons for eliminating PST files: 



PST files can cause space issues in a number of different ways. To start with each user that drags and drops a copy of an email sent to a distribution list to a PST will be storing their very own copy of that mail. As the data is stored locally, or on a network drive even, there is no single instance storage of that data. This is also the way that Exchange 2013 has headed, so, some organisations might not see this as a particularly bad thing. Besides storage is cheap, right?  (Might not be a good idea to mention that to your storage team though!) However, a lesser known issue with PST files is that each item typically has an HTML and a text body.  So large emails, perhaps replies to replies to replies to replies, leading to big message bodies take up almost twice the space in a PST file than they would do in an Exchange database.

Do you know in your organisation how many PST files there are? And how much space they take up?

Inability to search


Finding a particular email from even a few weeks ago is a challenge many people face. Even when the powerful indexing which is available through Outlook has indexed all the items in a mailbox it can sometimes take a little bit of time to find the particular mail of interest. Now compound that type of issue with half a dozen, or more, PST files.  You can quickly see how scouring for a particular mail is going to take a very long time. If the PST files are permanently attached to Outlook it will do a good job of indexing them, but still, as we see below duplicate copies of data across multiple PST files can still cloud the successful finding of particular messages.

How do your users find old mails that they have moved to PST files?



PST files invariably lead to duplication: Duplicate copies of mails within a particular PST file, and more troublesome is multiple copies of data across multiple PST files. In many situations you may have a PST file called 2013, and early in the year you copy or move lots of data from your mailbox to the PST. Later in the year you make a backup copy of it, and add yet more data to the PST, and the same even further into the year. But these copies and the currently active PST file contain largely the same data, with some delta at the end of it. These quickly add up to problems when trying to find emails, corruption becomes more common (as the backup copies are likely to be kept on the network and accessed across it, which is never a good idea) and the size of the files continue to grow.

How do your users make backup copies of PST files? Do these ever get cleared down by users? Are they kept in one location or does the location change over time as users develop different ideas (eg network storage for a while, then suddenly they are all on the users PC, then just as quickly they're all copied to USB pen drives)?



In the past PST files would frequently get corrupt as they approach 2 GB. This was the original limit of PST files. Work done by Microsoft, and several revisions later, PST files are a little bit better, but still corruption of the file is not unheard of. Sometimes the corruption can be repaired using a utility like ScanPST or third party utilities which might have been purchased. It's a risky business though, and often times because of the possibility of corruption, users will make multiple copies of PST files in multiple locations, adding to the issue of duplicates and compounding the space used by the sprawling PST file-estate.

Do you know how big the biggest 10-20 PST files are in your environment? Are they accessible and working correctly? Do you know how many corrupt PST files exist in your environment which can't even be opened successfully?



PST files are only accessible via Outlook, and not for example, when using Outlook Web App, or a mobile device. They're also only available if you can reach the PST file itself, and by that I mean if it is stored on a USB key that you forgot to bring to work one day, then you can't access the data. Sometimes remembering where the files are on network drives also leads to PST files ending up being inaccessible just because they've been forgotten about.

Do you have a lot of people that use Outlook Web App? How do they look for 'old' data which has been migrated to PST files?


In many organisations PST files still take up a lot of storage space on expensive server hardware and network attached storage. But for some, the space usage is only the tip of the iceberg when you begin to look at the PST problem.  The bigger problems are accessibility and searchability of the data contained in dozens of PST files-per-user.

What reasons does your organisation have to get rid of PSTs? 

Level 4

Nice article.Thank you!

Not applicable

Storage is cheap! (I like that one). Though the price has come down, you've made a good point about duplicates. I'll keep this is mind next time I need to consider network storage.

Level 2
Employee Accredited

Yes good article.

Version history
Last update:
‎10-20-2013 10:33 PM
Updated by: