List all DL's in on-prem Exchange with Zero members

Hey there, ActiveDirectory module is a decent option for this task in on-premises:

Get-ADGroup -Property Members -Filter * -Server "{DC name}" | where {-not ($_.Members)}
# Repeat against a DC for each domain.

 Get-ADGroup lets you work with the Members AND MemberOf properties, which are very handy for these kinds of exercises.  But AD module can be difficult if you have multiple domains in the forest...

Enter Get-DistributionGroup, which is fantastic too.. You could try this:

# in Exchange Management Shell / remote PS Session to Exchange server):
Set-ADServerSettings -ViewEntireForest $true
$DGs = Get-DistributionGroup
$DGsWithoutMembers = foreach ($g in $DGs) {
    if ((Get-DistributionGroupMember $g.Guid.Guid -ResultSize 1 -WarningAction SilentlyContinue | Measure-Object).Count -eq 0) { $DGsWithoutMembers += $g }
}

# then inspect and/or export:
$DGsWithoutMembers | Select-Object DisplayName, PrimarySmtpAddress, RecipientTypeDetails, Guid
$DGsWithoutMembers | Select-Object DisplayName, PrimarySmtpAddress, RecipientTypeDetails, Guid | Export-Csv -Path ".\DGsWithoutMembers.csv" -NTI