Manual Outlook PST Import Process

As organizations continue to migrate their data from Outlook PST files back to mailboxes for storage and cost savings, compliance, data protection, and preparing for the new Outlook interface, manually importing PSTs using the provided free functions of Outlook may be a first step in testing the approach for an overall migration project.

We’ve put together this manual PST import process guide to provide a checklist of what’s needed and help determine if an automated tool is a better fit after manual testing. In these steps, we are focusing on Outlook PSTs dispersed throughout an environment, either connected and in-use in Outlook or disconnected and located on Windows endpoint devices and network shares. Please note that Microsoft does not support the use of PST files in Outlook over network shares, but in our experience, many users still use this type of access.

These steps below also include the typical time estimates both on the end user side as well as the IT administrator or engineering side:

Protect Network Bandwidth - Network QoS for PST uploads (2 – 8 weeks for IT and Network Admins)

When allowing users to manually migrate PST files to M365 and avoid overloading your Internet links, setting up QoS (quality of service) policies to M365 is needed. There are two approaches for this; at the network level and at the Windows endpoint level:

Network level

1. Contact your network engineering team to determine which QoS options are available to use with their network equipment.
2. Work with them to determine the network path from the Windows endpoints in your organization to their mailboxes on either your on-prem Exchange servers or your Exchange Online servers in the M365 tenant. This may be over the Internet, through an ExpressRoute connection, or other links depending on your organization's network topology.
3. Have them determine the average utilization of the upstream links (connecting to Exchange servers hosting mailboxes – cloud or on-prem) to find the available bandwidth above and beyond what’s typically used. Historical reports are valuable here for identifying trends over time instead of simply the current averages.
4. Take the available average upstream bandwidth and divide it across the number of Outlook endpoints migrating PST files. For example, if the total upstream bandwidth available is 1Gb/s and is 60% utilized on average, then ~400Mb/s upstream is available for import processes. At 2Mb/s per endpoint importing PSTs, 200 endpoints could be allowed to import at concurrently.
5. Have your network engineering team create QoS policies for these endpoints to your Exchange servers to limit the upstream bandwidth appropriately.
6. Test these policies to ensure they have the desired effect and do not negatively impact any other applications or the end user experience for their common workflows.
7. After successfully testing, have your networking team deploy the policies across the network infrastructure following your change control policies.

Windows Endpoint level

1. Contact your network engineering team and have them determine the average utilization of the upstream links (connecting to Exchange servers hosting mailboxes – cloud or on-prem) to find the available bandwidth.
2. Work with them to determine the network path from the Windows endpoints in your organization to their mailboxes on either your on-prem Exchange servers or your Exchange Online servers in the M365 tenant. This may be over the Internet, through an ExpressRoute connection, or other links depending on your organization's network topology.
3. Take the available average upstream bandwidth and divide it across the number of Outlook endpoints that will be migrating PST files. For example, if the total upstream bandwidth available is 1Gb/s and is 60% utilized on average, then ~400Mb/s upstream is available for import processes. At 2Mb/s per endpoint importing PSTs, up to 200 endpoints could be allowed to import at the same time.
4. Create a Windows GPO for QoS – Computer Configuration -> Windows Settings -> Policy-Based QoS -> right-click and select “Create new policy”.
5. Name the policy, enter in the outbound throttle rate, specify the Outlook.exe application, and source and destination IP addresses and ports if needed.
6. Test the policy to ensure they have the desired effect and do not negatively impact any other applications or the end user experience for their common workflows.
7. After successfully testing, have your endpoint management team deploy the policies across Outlook endpoint devices which will be performing manual imports following your change control policies.

Discover the PST files on your system and network drives (30 minutes - 1 hour for Users)

1. Open Outlook data file settings and get the properties of any connected PST files to find their location.
2. Search your local drives by using the “dir /s *.pst” command from a command prompt for each drive – this usually completes in a few seconds versus using a File Explorer search for *.pst which can take 5 – 20 minutes to complete.
3. Search your network or home drives using the same approach as above.
4. If you find any PSTs that are 271,360 bytes in size, these are most likely empty PST files and can be deleted. These will show as 265Kb in Windows Explorer file lists.
5. If you find PST files smaller than this size, they could be the files used by other applications and should be left unless you are certain they can be removed.
6. If you find PST files named “SharePoint Lists” or “Internet Calendar Subscriptions”, these are integration PST files that do not contain data so should be left. If they have not been modified for an extended amount of time, they may no longer be in use and could be deleted if desired.
7. Record all of the PSTs with their file sizes and locations for the following steps.

Determine which PST files you want to import: (1 – 2 hours for Users)

1. If you have duplicate PST files, confirm they are duplicates or import each of them if you’re not certain.
2. To determine what data is in each file, check for duplicates, and verify that you want to import the data, open each PST by connecting it in Outlook.
3. If you have PST files from other users/staff (users who have left, etc.), determine if you want to import those into your mailbox.
4. Determine how far back / how old of PST files you want to import, respecting regulatory standards (such as less than 7 years), and if so, separate/remove the older PST files while tracking the ones you want to import.
5. Update the PST list you recorded in the discovery step.

Ensure PSTs are Valid – Check for Corrupt PST files (Depends on size, network bandwidth to file shares and amount of corruption  - Use 10 min per file + 2 min per GB)

1. If you have PST files that can’t be opened or show errors in Outlook as you browse through them, these files are probably corrupt – more on PST Corruption here.
2. Copy the corrupt PST files locally on your Windows endpoint, ensuring that you have enough space locally for the PST file including twice the space to allow for backup copies during the repair process.
3. To ensure an import is not canceled due to corruption, it is suggested that you disconnect all PSTs from Outlook.
   1. Be sure that Outlook has released the lock on the files by either waiting 15 – 90 minutes or closing Outlook.
4. Find the SCANPST.EXE application which is included in your Outlook client folder.
5. Launch SCANPST.EXE, select the PST you want to scan, and select start.
6. SCANPST will return the results of the scan, recommend a repair, and allow you to create a backup copy of the PST file.
7. Click Repair. The repair process can take minutes to hours depending on the size of the PST file and the amount of corrupt data in the file.
8. Once each PST is repaired, open it in Outlook to confirm it can be read and accessed for import.

Ensure Sufficient Space - Mailbox space & retention policies (1  - 2 hours for Users)

1. Check in Outlook to confirm whether you have only a primary mailbox and/or an Online Archive. Your mailbox will show at the top left in the tree view with your email address and mail folders below it. If you have an Online Archive as well, it will show at the bottom of the tree view with a top-level that looks like “Online Archive – JonS@company.com”.
2. Determine if there is enough available space in your primary mailbox for all of the PST files you need to import. Importing to the primary mailbox will be the fastest option with the best user experience. You can find this in Outlook by selecting the File menu, then Info. The Mailbox Settings will show the amount of free space in your mailbox; for example, 64.7 GB Free of 99GB.
3. If there is enough space for the PST files from the list you create AND the existing email in your mailbox without hitting quota limits, you can proceed with the imports.
4. If you do not have an Online Archive and there is not enough space for existing mail data plus the PSTs you need to import, please contact your IT team for the next steps.
5. If you have an Online Archive and there is not enough space for existing mail data plus the PSTs you need to import, you can create a retention policy in Outlook to automatically move mail data from your primary mailbox to your Online Archive based on how old the mail data is. To do this, open your mailbox in Outlook for the Web through a browser, click on the gear icon to access settings, select Mail, then Retention Policies. You will be shown any existing policies applied to your mailbox. You can select “Add new policy” and select from the list, such as “Personal 1 year move to archive” which will move any mail data in your mailbox that’s older than one year to your online archive, freeing up space in your primary mailbox for PST imports.
6. If you have an Online Archive and there is not enough space for existing mail data plus the PSTs you need to import, you could attempt to import PSTs directly to your Online Archive, BUT this is not recommended as this import process could take 2 – 4 times longer and cause hangs and slowness to the Outlook application during the import.

Import Process (1 hour for every 2 Gigabytes of PST data on average)

1. Once you have completed the steps up to this point, ensure you have your updated PST list with the files you will be importing recorded.
2. Since the Outlook import process prevents using Outlook during the import, set aside time to import each file when you don’t need to use Outlook for work tasks.
3. In your mailbox, create a new folder for each PST file you will be importing; you will use these later.
4. Select the folder you created for the PST file you will be importing on Outlook – important - do this before the next step!
5. In Outlook, select the File Menu, then Open & Export, then Import/Export.
6. Follow the wizard window that appears and select import from another program or file.
7. Select to import from an Outlook Data File (.pst).
8. Select the PST file you want to import and select the “Do not import duplicates” radio button which is the typical recommendation.
9. Select the folder to import from in the PST (the top level will import all), then select “Import items into the current folder” – make sure you selected the correct folder in your mailbox that corresponds to the PST file you’re importing from step 4 above.
10. Click Finish and the import for this PST file will commence with a status bar shown in Outlook.
11. Once complete, ensure the data from the PST file is in the corresponding folder in Outlook under your mailbox.
12. Track which PST files have been completed.
13. Delete the PST files that have successfully been imported into your mailbox
14. Repeat this process for all PSTs until all are imported, tracked, and deleted.

Summary

In the end, manual PST imports require about 2+ weeks from IT Admins/Network teams to prepare the network for uploads and at least 4 hours for the end user if they only have one 2 GB PST file that is not corrupt.

The average we typically see per user is three PST files with a total of 15 GB of data, which comes out to ~11 hours of import time per user assuming 2Mb/s of available upload speed.

The Why of PST Migrator

If this manual process is a fit and valuable for your use case, you have the tools and steps needed to perform it.

If you want every step if this process automated and run behind the scenes with no end-user impact or intervention, we created PST Migrator for this reason and would love to show you how easy it is.