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How To: Exporting Office 365 Mailboxes to PST Files

To Export a PST file from Exchange Online, choose the Export to PST from Exchange Online on the main screen and click next.


Note on the Next Screen you must enter in the local Exchange details, if you are exporting from On Premise Exchange.

On the next screen you will be prompted for your Administration Credentials for Office 365.  This account must have a mailbox.


  • If the Show Mailbox Size checkbox is selected, it can take much longer to load the list of mailboxes.
  • In larger organizations you can use MAPI to Get Mailboxes from the GAL instead of Remote PowerShell.  Checking this option results in a small performance improvement.
  • If you have a license key for over 1000 users, you can skip Getting All Mailboxes via Remote PowerShell.  You will then have to search for the mailboxes or use a CSV file on the next screen.

The next screen has several options which are described below:


Click the Select Mailbox button to select the mailbox(es) that need to be fixed and click Select Mailbox to add the mailboxes to the export list.

  • Use Ctrl-A to select all mailboxes or hold down Ctrl to select multiple mailboxes


When using the CSV option you CSV file needs valid header row.

An example of a csv with a valid header row should look like:


Valid header rows:

SourceMailbox : Primary SMTP address of the Mailbox to export
ExportDirectory : Directory to save the PST to
ExportMailbox : boolean (true,false) to indicate to Export the Mailbox
ExportArchive : boolean (true,false) to indicate to Export the Archive
ExportDumpster : boolean (true,false) to indicate to Export the Dumpster
Excludefolders : contains folders to exclude for the export separated with a ; eg \Inbox;\SendItems;\Contacts
Excludesubfolders : if true the subfolders of the exclude folder will be excluded as well

You can also use the Load from History button to load a previous list of mailboxes that were queued to be fixed.  This is useful the Exchange Migrator crashes or something in the middle of a migration.

Once a mailbox, or group of mailboxes, is selected you can choose to export the mailbox, archive, or dumpster.  You can select one of these options or a combination.

The Use Direct Discover checkbox should be selected if the Autodiscover record for the domain is not pointing to Office 365.  If selected the Exchange Migrator will attempt to connect directly to Office 365, bypassing the Autodiscover process.

The Use MAPI Only option will only allow the Exchange Migrator to use MAPI.  Normally it uses a combination of EWS / MAPI  this forces it to use only MAPI.

In the Export File Options area click the Select Export Directory button to define where the PST files should be exported to.

You can either create a new PST file or use an existing PST file.  If you choose an existing PST file, it will not import duplicate items (assuming the PST file was created by Exchange Migrator).  You can use the existing PST option to resume a failed or interrupted migration.

The option is to select the size at which a PST file should be split.  The default size is 20,000 which equates to 20 GB.  You can increase this to say 50,000 GB but then you increase the size the likelihood of your chances to fail increases.

Folder Filtering

  • Filter Folders - folders to exclude for the export separated with a ; eg \Inbox;\SendItems;\Contacts
  • Exclude Folders - if set to true, excludes folders from the mailbox

The Email Status Notifications will just email the administrator when the export process is complete.

Once the options are selected click the Add to Export Queue button to queue up the exports.  If you are ready to export the archive, click the Start Export button.

When the export starts if you get prompted for a username and password enter the Office 365 Administrator username you entered previously on the remote PowerShell Screen and check the box to remember the credentials.  You must check the box to remember the credentials when prompted or the export won’t work.

An Important Note about Exporting PST’s from the 2013 version of Office 365

When exporting mailboxes to PST files from Office 365, the admin account is automatically granted access to the mailbox and that access is then removed when the export is complete.  With the 2010 version of Office 365 this permission change took place almost immediately.  With the 2013 version it can take several minutes, and if you try and connect before the permissions are applied, it seems to take even longer before you can access the mailbox.  While we still add permissions if they don’t exist, we wait 15 minutes before trying to access the mailbox after adding the permissions.  If you are doing a large number of exports we highly recommend adding the permissions ahead of time to avoid this delay.

Grant Full Access to All Mailboxes

To Grant full Access to a Mailbox in Office 365 you must first connect to the remote PowerShell, by typing the 3 commands in your local PowerShell:


$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri -Credential $o365cred -Authentication Basic -AllowRedirection

Import-PSSession $session

After you are connected, run the following command to give your admin account full access to all mailboxes:

Get-Mailbox -resultsize unlimited| Add-mailboxpermission -user -AccessRights FullAccess -Automapping $false

To later remove the permissions, run the following command:
Get-Mailbox -resultsize unlimited| Remove-mailboxpermission -user -AccessRights FullAccess


Updated: April 16, 2016

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