Deep Sixing PST Files
Published Jul 08 2015 06:00 AM 36.6K Views

A little over two years ago we wrote about removing PSTs from your organization and gave you a tool to assist you with that endeavor. .PST, Time to Walk the Plank. Since then, we’ve updated the tool with some new features and functionality. In this blog, we are going to give you:

  1. More reasons to get rid of PST files.
  2. What to do with the data in the PST files.
  3. How to move the PST data to its new location.

More Reasons to get rid of PST files.

Without further ado, let’s talk a bit about why you want to get rid of PST files.

Corporate Security and Compliance.

  1. PST files are created by users and are unmanaged data. Most organizations have very little insight into where PSTs are created, how the users retain the files, where the files are kept, and exactly how much data is in those files.
  2. PST files usurp your well defined data retention policies. Exchange Data Retention Policies do not apply to data residing within PST files, and you cannot set retention tags in PST files.
  3. Outside of the maximum file size for a PST, currently 50 Gigabytes, they are not limited in size.
  4. A PST from one machine or user can easily be opened by another user off the network. They can be stored on portable media that can be lost or stolen. Thumb Drives, USB storage media, DVD, personal cloud storage. This is a data leakage risk, even if they are password protected.
  5. Depending on your corporate backup strategy, they may not be backed up anywhere. This can result in data loss if the user’s computer has a disk issue.
  6. Data within PST files is not discoverable with built in Exchange Discovery tools. This creates a complex discovery issue for legal departments which can lead to a very expensive discovery process.
  7. More about the importance of Records Management can be found in a very old Exchange Team Blog here.

User Experience

  1. Users with multiple PST files have a disjointed experience when switching machines or using OWA. Because a PST only resides on a single computer, users are limited on how they can interact with that data. It today’s mobile workforce, with smartphones, tablets, laptops and workstations, this can result in data being strewn across devices and the user not having the data they need when they need it.
  2. Outlook Rules that work with a PST file will only work on the computer where that PST resides and Outlook must be running for the rule to fire properly.
  3. Disk Space. PSTs can be up to 50 GBs and users can create multiple different PSTs which can impact disk space on the workstation or device.

Great, you’ve talked me into it, HOW do I get rid of PST files?

Glad you asked, but before we get started you have to make some decisions.

Where do you want to put the data?

Once you decide where you want to put the data, we can work on methods to get it there?

What to do with the data in your PST files.

Now that you have decided it is time for PSTs to Walk the Plank; let’s decide where to put all that data. In general, you have 4 options.

First, you have to decide WHERE you want to store this data?

  1. User Mailbox
  2. Archive Mailbox Locally
  3. Archive Mailbox in the Cloud
  4. Delete, Delete, Delete

Option 1: Keep it simple. Given the mailbox size capabilities of Exchange 2013, you could pull all that mail back into the users’ mailboxes.


  • Easy. Pulling all that PST data back into the mailbox is very easy using the PST capture tool—as long as you have the space. Also keeping it in a single mailbox reduces the management complexity as each user only has a single mailbox associated with their account.
  • Discoverability of data. Mailboxes are searchable via native Exchange Discovery Tools.
  • Manageability of data. Mailbox data is subject to data retention policies.
  • No separation of data. Exchange 2013 and later is designed to handle large mailboxes (100+ GB in size). From a client perspective, all clients can access the data and you can control the OST size with the Outlook 2013 Sync Slider.


  • Cost. Increasing the mailbox sizes for all users and keeping multiple copies of that data on server storage can get quite costly if you are not deploying commodity hardware as recommended in the Preferred Architecture.
  • Overhead: Database and log file disk space management. During the ingestion phase, the database and log files will grow quickly if the process is not managed.
  • Large OST footprint with legacy clients. If you are deploying legacy Outlook versions (2010 or prior) or using the Outlook:Mac client, you cannot control the size of the cached mailbox.

Option 2: Keep it Separate. With Exchange 2013 you can create an archive mailbox and import all the PST data into it.


  • Discoverability of data. Archive Mailboxes are searchable via the native Exchange Discovery tools.
  • Archive Mailbox Data is Manageable. Aging and retention policies apply to both the Mailbox and Archive Mailbox and not to PSTs.
  • Security. The data is secure on your Exchange servers, not on users’ local drives.
  • Safety. The data’s resiliency is handled by continuous replication.
  • Access. The Archive Mailbox is accessible by the user on most machines where they have mailbox access, this includes OWA (access varies by client. Outlook 2007 SP2 with February 2011 cumulative update and above for Outlook for PC).


  • Storage costs. You are still importing all of that data into your Enterprise Mail environment. This storage includes, disk space for the data, copies of the data, and backups of the data.

Option 3: Keep it in Office 365. With Exchange 2013 and Office 365, you can put the archive in the cloud—even if the primary mailbox is still On-Premises.


  • Discoverability of data. Archive Mailboxes are searchable via the native Exchange Discovery tools.
  • Reduce Storage costs. With an Enterprise CAL Suite, Archive Mailboxes are included at no extra cost. Enterprise CAL Suite Details. Think about it, Unlimited Archive storage space for your users.
  • Archive Mailbox Data is Manageable. You can apply aging and retention policies.
  • Security. The data is secure on Office 365 servers, not on users’ local drives.
  • Safety. The data is redundant and safe in the Office 365 cloud.
  • Access. The Archive Mailbox is accessible by the user on most machines where they have mailbox access, this includes OWA (access varies by client. Outlook 2007 SP2 with February 2011 cumulative update and above for Outlook for PC).
  • Reduced Storage Hardware. Exchange Online Archive uses Office Online storage and negates the need to build additional storage for the ingested PSTs.
  • Reduced Management cost s. Once the Online Archives are set up, the back end management of the cloud storage is done by Microsoft.


  • Initial Setup. Yes, there is a bit more setup involved in going to the cloud, but that effort is going to be considerably less than architecting and adding the storage for all of your PST files.

Option 4: Delete them all. Yes, this is actually an option.


  • Really easy to find and delete PST files.


  • Lost data. All those PST files were kept for a reason. Some of that data could be business critical.
  • Angry users. Do I need to explain this point? Torches and Pitchforks anyone?

Those are your main options for addressing PST data. In Part 3, we’ll discuss some methods to get the data to the desired location.

How to move the PST data to its new location

This time, I’ll talk about a strategy.

  1. Announce the Policy.
  2. Lock the PSTs
  3. Move the data and remove PSTs from workstations.

Step 1: Announce the Policy


Once you have determined your data retention and PST storage plan, you need to announce it. This message should come from the policy makers, Legal, Business, etc, NOT the IT department. Pointing to the User Experience issues from Part 1 of this series will go a long way toward easy user acceptance and adoption.

Step 2: Lock the PST files

No sense in getting rid of them if the users can keep putting them back. You can use the following registry keys \ Outlook Policies to control the behavior before, during, and after you move everything to its final location.

  1. DisablePST – Prevents users from adding PSTs to Outlook profiles.
  2. PSTDisableGrow –Prevents user from adding content to PST files.
  3. DisableCrossAccountCopy – Prevents users from copying data into or out of PST files.
  4. DisableCopyToFileSystem – Prevents users from copying mail to a File System.

Further details on the options to keep users from adding data to PST files -

Step 3: Moving the current PST file data. Three options.

  1. Automate the Move with PST Capture.
  2. Allow your users to move their data.
  3. Upload or ship your PST files to Microsoft and have us import it for you.

Option 1: Automate the Move with the PST Capture Tool.

The PST Capture tool will discover all PST files in your organization. It will gather them into a consolidated location. It will import them to the location you desire, Mailbox, Archive Mailbox, Cloud Archive Mailbox.

Option 2: Allow your users to move their data into their Mailbox or Archive Mailbox.

Wait? What? You just told me about that amazing automated tool, why would I make my users manually import their data?

The tool is great, but it does have some limitations that may not work for all customers.

  1. All or nothing. The tool imports all mail from a PST with no filters for content or age.
  2. Agent on every desktop. The tool requires an agent install on every desktop.
  3. Outlook must be shut down for the PST Capture to finalize the PST move.

While this option works, it creates a significant amount of administrative overhead. You have to manage the process:

  1. The messaging to the users about how and where to move the data.
  2. The issues around database and log management if they are uploading On-Premises
  3. The timelines for each of the settings for locking the PST.
  4. Following up with the users.
  5. Following up with the users.
  6. Following up with the users.

In short, yes, this can work, but will drag out the process significantly.

Option 3: Have Microsoft put your PSTs in your Office 365 Mailbox or Archive Mailboxes for you.

Yes, you heard that right, Microsoft will put them in the cloud for you. This is a great option if you have a large amount of data to upload. You can directly upload the PST files via Azure AZCopy Tool OR ship the disks to us. Typically, we recommend the disk shipping service for data over 10TB.


  1. The PST files. For either drive shipping or network upload, you need to collect them so that they can be copied into the hard drives or uploaded to the cloud storage destination.
  2. Office 365 tenant with active users and mailboxes for all of the users who will have data imported. This option is currently only available if the mailbox is already in Office 365.
  3. PST Mapping File.
  4. A User Account with Mailbox Import Export admin role.


  1. Hard Drive: Only 3.5 inch SATA II/III hard drives are supported for use with the PST Import service. Hard drives larger than 4TB are not supported. For import jobs, only the first data volume on the drive will be processed. The data volume must be formatted with NTFS. You can attach a SATA II/III disk externally to most computers using a SATA II/III USB Adapter.
  2. BitLocker encryption: All data stored on hard drives must be encrypted using BitLocker with encryption keys protected with numerical passwords. The Office 365 drive preparation tool will help with the encryption. This can be found in the Office 365 Admin Center under the Import tab.
  3. A carrier account for shipping if drive shipping is your preferred method.

Details of the Office 365 Import service are here:

Other relevant articles:

Mike Ferencak
Senior Premier Field Engineer

Version history
Last update:
‎Jul 01 2019 04:23 PM
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