Apply Exchange Public Folder Permission import via Import-CliXML

I did run into the situation that I lost all my public folder permissions which were assigned via groups.

Before the migration started from our MSEX2016 server to Office 365, all the permissions got exported to a XML file, what I think (described on this Microsoft page) happened with the following command:

Get-PublicFolder -Recurse -ResultSize Unlimited | Get-PublicFolderClientPermission | Select-Object Identity,User,AccessRights -ExpandProperty AccessRights | Export-CliXML OnPrem_PFPerms.xml

The output file "OnPrem_PFPerms.xml" has about 5 GB. That sounds a lot to me for permissions only on a about 300 GB PF structure, but maybe is its huge size cause by the complexity of the XML format. 7-Zip compression brings it down to 25 MB, means there is a lot of redundant data in it.

On our MSEX2010 which got migrated to MSEX2016 before is a "Legacy_PFPerms.xml" file with about 500 MB.

What would be the proper PowerShell command to apply all the permissions from the XML file to the public folder structure on the Office 365 / Exchange online?

I guess Import-CliXML would do the job somehow, but I am not that familiar with PowerShell to build the right command.

Solution 1:

Finally the following PowerShell script allowed me to apply all the permissions from the XML file to the public folder structure. Thanks to Ivan_Wang who led me to the right direction with his answer.

$pfs = Import-Clixml -Path OnPrem_PFPerms.xml

foreach($pf in $pfs)
{
Add-PublicFolderClientPermission -Identity ("\" + $($pf.Identity.MapiFolderPath -join "\")) -User $pf.User.DisplayName -AccessRights $pf.AccessRights[0].ToString()
}

Is is also possible to split that up in multiple PowerShell sessions to apply the changes faster since it runs pretty slow.

1. PS session: foreach($pf in $pfs[0..2000]) ...

2. PS session: foreach($pf in $pfs[2001..4000])...

...

Do not run too many sessions at one, otherwise it will interrupt the connection to Exchange Online with the following message: The request is not serviced on the server. Your request is too frequent.

Solution 2:

What're the properties included in the .xml file? If there are Identity and User, AccessRights, you could try:

$pfs = Import-Clixml -Path OnPrem_PFPerms.xml
foreach($pf in $pfs)
{
Add-PublicFolderClientPermission -Identity $pf.Identity -User $pf.User -AccessRights $pf.AccessRights
}

Based on your command above, it seems to export only the AccessRights object. If so, you may need to export the current ACL list in Exchange Online to a .csv file:

Get-PublicFolder -Recurse -ResultSize Unlimited | Get-PublicFolderClientPermission | Select-Object Identity,User,@{n="AccessRights";e={[String]($_.AccessRights)}} -ExpandProperty AccessRights | Export-Csv pf.csv

And assign permissions of the public folders to your users again via PowerShell(For existing permission entries, PowerShell will report a warning: An existing permission entry was found for user):

$pfs = Import-Csv pf.csv
foreach($pf in $pfs)
{
Add-PublicFolderClientPermission -Identity $pf.Identity -User $pf.User -AccessRights $pf.AccessRights
}