Trying to get the total size of a users mailbox

Question

I am trying to get the total size of a mail box.

I can get the size of individual folders, for example the Inbox like this:
Get-MgUserMailFolder -UserId $user.Id -All | Where-Object { $_.WellKnownName -eq 'inbox' }
This returns AdditionalProperties.sizeInBytes.

I should be able, I think, to connect to the root folder and get the corresponding value.
Get-MgUserMailFolder -UserId $user.Id -All | Where-Object { $_.WellKnownName -eq 'msgfolderroot' }.
But this returns nothing, no error.
According to https://learn.microsoft.com/en-us/graph/api/resources/mailfolder?view=graph-rest-1.0, msgfolderroot is a wellknownfolder.

I have tried

$folder = Get-MgUserMailFolder -UserId $user.Id -All | Where-Object { $.WellKnownName -eq 'inbox' }
This gives me $folder.ParentFolderId which should be the root.
Get-MgUserMailFolder -UserId $user.Id -All | Where-Object { $.id -eq $_.ParentFolderId }
Returns nothing.

Is there another way?

Regards
Mikael

Answer 1

I think the problem is that when you use

$folder = Get-MgUserMailFolder -UserId $user.Id   

It will start the search at msgfolderroot but it won't include that root folder in the result if you just want to bind to the root folder use

Get-MgUserMailFolder  
   -MailFolderId <String>  
   -UserId <String>  

where MailFolderId would be the $folder.ParentFolderId you get from the Inbox

What that cmdlet really needs is another parameter where you can pass in the WellKnownName rather the doing a search and using Where-Object

That said the AdditionalProperties.sizeInBytes should just be the size of the Root folder not the Mailbox if you want to get true mailbox size then use https://learn.microsoft.com/en-us/graph/api/reportroot-getmailboxusagedetail?view=graph-rest-1.0