Get a list of mailboxes where AD group has permissions - powershell

Question

I am trying to get a list of mailboxes that have a an AD group listed in their permissions.
All the AD groups I am interested in start with the same 3 characters.
I have....
get-mailbox -resultsize unlimited | Get-MailboxPermission | where {$_.user.tostring() -like "xxx*"} | out-file $file -append -noclobber -encoding ascii
but it doesn't seem to put anything in the file
What am I doing wrong?
TIA
Andy

Answer 1

I have a sneaking feeling there will be more questions after this but part of the issue is you loose the mailbox details when they are being passed into the cmdlet Get-MailboxPermission. If you match criteria was a little more refined your output would just be the groups that matched but not to which mailbox.
$file = "c:\temp\test.csv"
$matchPrefix = [regex]::Escape("Ex") # We use escape incase of special charaters in regex. Period would be one to expect.
$regex = "YOURDOMAIN\\$matchPrefix" # Keep those backslashes
Get-Mailbox mc* | ForEach-Object{
$results = $_ | Get-MailboxPermission | Where-Object{$_.User.ToString() -match $regex}
If($results){$_}
} | Select Name,Alias | Export-CSV $file -Append -NoTypeInformation
This will take every mailbox and check each for the presence of the group/user. Using $regex we check each of the located user/groups. If they are present then the -match would return True satisfying the Where block and the mailbox is passed in the pipeline to be exported.
For the export we just send the mailbox name and alias to a csv file specified by $file
Caveats
-Append is available in PowerShell 3.0 which you exchange might not have. I could just be removed.
Assumptions
I am assuming you want just the mailboxes that match the group prefix you specify. If you want the actual groups that match it is possible with a little extra logic. I would like to know if what I suggest is sufficient before I guess more.

Answer 2

This code works, and it is also clear as to which mailbox these permissions belong:
get-mailbox -resultsize 1000 | foreach{
Write-Host $_.PrimarySMTPAddress -ForegroundColor Green;
$permissions = Get-MailboxPermission $_.PrimarySMTPAddress | ?{$_.User -match "Ryan"}
if($permissions){
$permissions | FT -AutoSize;
$_.PrimarySmtpAddress | Out-File C:\Test.txt -append -noclobber -encoding ascii;
$permissions | FT -AutoSize | Out-File C:\Test.txt -append -noclobber -encoding ascii;
}
}
Please note: I checked to see what $_.user.tostring() produces in order to know what I am looking for with respect to the "match" Boolean logic.