Powershell to find users with SendAs permission on Public folders

Question

I have been having great difficulty getting this to work and I am baffled as to what it is I am missing!
We have a lot of public folders and some users have SendAs permissions - we want to find them.
I have found various suggestions on line like these two lines -
Get-PublicFolder -Recurse -ResultSize 10 | Get-PublicFolderClientPermission | Select Identity, User, AccessRights
this works and lists the folders and all user permissions but my attempts to filter it fail
Get-PublicFolder -Recurse -ResultSize 10 | Get-PublicFolderClientPermission | Select Identity, User, AccessRights | Export-CSV "PublicFolderPermissions.csv" -NoTypeInformation
this I is claimed to work (and I would expect it to) but instead fills my CSV with folder and user information but the AccessRights value (clearly displayed in the first example) is replaced by this
"Microsoft.Exchange.Data.MultiValuedProperty`1[Microsoft.Exchange.Management.MapiTasks.PublicFolderAccessRight]"
So I tried this
get-publicFolder -recurse -ResultSize 10 | Get-PublicFolderClientPermission | foreach-object  {write-host $_.Identity, $_.User, $_.AccessRights}
which works but any attempt to redirect to a file, export to csv or add-content to a file either outputs nothing or outputs everything but gives the accessrights as "Microsoft.Exchange.Data.MultiValuedProperty`1[Microsoft.Exchange.Management.MapiTasks.PublicFolderAccessRight]"
does anyone have any idea how I get the information I want into a CSV (where I can then filter it) or filter the results by SendAs and save to CSV?
Obviously the -ResultSize 10 if for testing and will be replaced with Unlimited.
I assume  my filters on SendAs always failed because rather than passing along $_.AccessRights as the string I see on screen I get the string I see in the CSV so nothing matches SendAs.
I am clearly missing something obvious so any help would be appreciated.

Answer 1

That has got me close to it I think but identity returns something like "******.net/Microsoft Exchange System Objects/Info" where "Info" is a public folder under a folder called "Postroom"
This does at least restricts the results to users having SendAs permission so that is a lot of progress
Get-publicfolder does translate the returned identity to a path so that should help
Unfortunately piping to export-csv does not return the desired results
redirect to file does save the information though so that should be helpful
Many thanks
Yes, took all night but I now have enough information to work on