Command to check specific user is a part of certain group or not - powershell

Question

List all users that have mailboxes but are not in a group called Metalogix*. I need a PowerShell script that will check whether specific user is a part of certain group or not and if the user is part of any of those groups.
I already have working script:
Import-Module ActiveDirectory
$Users = Get-Mailbox -ResultSize "unlimited"
$Group = "Metalogix*"
foreach ($user in $Users) {
$Check = Get-ADPrincipalGroupMembership -Identity $User.sAMAccountName |
? { $_.Name -like $Group }
if ($Check -eq $null) {
Write-Output "$User.sAMAccountName is NOT part of this group"
} else {
$Results = Get-Mailbox -Identity $User.sAMAccountName |
select Name, sAMAccountName, PrimarySmtpAddress, Database |
Export-csv "c:\results1.csv" -NTI -Append
}
}
But script doesn't list groups recursively, e.g tester4-6 are members of 'Test Group 2', which is a member of 'Test Group 1'. The rest are direct. Just I can see direct membership, not recursive membership.
2nd question : I want to get all users with samaccountname that begins with "STR" prefix.
Test Group 1
tester1
tester2
-> Test Group 2
tester4
tester6

Answer 1

I'd probably use a recursive function. Something like this:
function Test-GroupMembership {
Param(
[Parameter(Mandatory=$true)]
[string]$Identity,
[Parameter(Mandatory=$true)]
[string]$Name
)
$groups = Get-ADPrincipalGroupMembership -Identity $Identity
if ($groups | Where-Object { $_.Name -like $Name }) {
return $true
} elseif ($groups -ne $null) {
foreach ($g in $groups) {
if (Test-GroupMembership -Identity $g -Name $Name) {
return $true
}
}
}
return $false
}

Answer 2

Get-ADPrincipalGroupMembership isn't recursive, but Get-ADGroupMember is.
$Users = Get-Mailbox -ResultSize "unlimited"
$Group = 'Metalogix*'
$GroupMembers = Get-ADGroupMember -Identity $Group | Get-ADGroupMember -Recursive | Select-Object -ExpandProperty samAccountName
foreach ($User in $Users) {
if ($User -in $GroupMembers) {
Write-Output "User $User is in group $Group."
}
else {
Write-Output "User $User is not in group $Group."
}
}
This is also more efficient because you're only fetching group membership once.
I'm away from my servers, so treat the above as pseudocode.