Export Office 365 Mailboxes to PST using eDiscovery

article #1052, updated 774 days ago


  1. There will be a ClickOnce application involved for the potentially huge download. If you use Firefox as I do, you’ll want the new Firefox plugin which makes ClickOnce work much better.
  2. Within the O365 tenant’s Exchange admin area, open Permissions, open Discovery Management, and make sure all of Legal Hold, Mailbox Import Export, and Mailbox Search are present. If any of these three are absent, add them. Then scroll down to the bottom, and add your admin login as a Member.
  3. Within the O365 tenant’s Security & Compliance admin area, open Permissions, open eDiscovery Manager. Scroll down to the bottom, and add your admin login as an eDiscovery Administrator.
  4. Log entirely off of the O365 console, to activate the above permissions. Occasionally activation may require 30 minutes or more, but often it is immediate after logoff/logon.
  5. Go back to Security & Compliance, open Search & investigation. Click on eDiscovery.
  6. Create a new case. Name it something like “Export mailbox Grom”, if it’s just one user by the name of Grom that you are exporting.
  7. Open the case. Click on the Search tab. Click the Plus. Name it “mailbox Grom” or something else appropriate. Add the user to search for. Search all sites. Search public folders if you want. Click next. Don’t enter any search delimiters here unless you want a limited result. Click Search. The search is created and begun automatically. It will show you how big the result is. This is the size of the download you will be doing. The download is done by the ClickOnce application, not the browser, but if it’s huge it’s still huge.
  8. Once the search is done, you’ll need to find a little icon in the row of icons just above the list of searches. It’s fourth from the right at this writing, it looks like an arrow pointing down to a dash. Click on that, it will give you the option to “Export the Results”, which you should do as well. This starts the export wizard.
  9. Best to export all items, excluding ones that have unrecognized format, are encrypted, or weren’t indexed for other reasons, unless you have definite reason and knowledge to do otherwise.
  10. One PST file for each mailbox.
  11. No de-duplication, just in case.
  12. Versions for SharePoint documents if you want. In certain circumstances this could get huge.
  13. Start export. Here, unfortunately, is where you learn whether or not the Permissions settings are fully active yet. If they are, it will work; if not, it will tell you that you don’t have permissions sufficient, and you will have to wait.
  14. Once it’s done, click on the Export tab, and then the Refresh double arrow circle. You should see a downloadable export file. Make sure it’s highlighted, and click “Download exported results”, the blue text on the right side towards the bottom.
  15. Click “Copy to clipboard” under the export key. You’ll need this as authentication for the ClickOnce application.
  16. Click “Download results”.
  17. I’m in Firefox, so I click on the button “ClickOnce Install”.
  18. The eDiscovery Export Tool runs. I paste in the export key, and browse to a good path for the download. Then I click Start. And it begins the download! Obviously it may take a very long time for multiple gigs to download, and it even may take the cloud server a few minutes to prepare the download before it starts. But once it starts it is able to use a very large amount of Internet bandwidth if you have it. On a large pipe I watched it run at a consistent 10,000+ KB/second — ten megabytes per second, or 80 megabits per second, or 36 gigabytes per hour; so very large exports are feasible.