Exchange Online – set default Retention Policy if null

# EDIT # I have updated this script due to an issue where multiple mailboxes are matched due to similar names, this line below with $mailboxes variable piped to the Set command uses Display Name for Identity which may not be unique. Script is updated to loop through the mailboxes using UPN for the Set command. Cheers! 🍺

$mailboxes | Set-Mailbox -RetentionPolicy $defaultpolicy.Name

I’ve come across several clients lately who are migrating to or have migrated to Exchange Online, and find some users have no retention policy set. This script can be scheduled in an Azure runbook to find enabled users with no policy and set it to the default policy. Replace ‘svc-runbookcred’ with your runbook credential name. Easily modified to connect to on premise Exchange; if you need any help just add a comment below! 🙂

# use TLS 1.2
[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12

# specify runbook credential name
$runbookcredential = 'svc-runbookcred'

# get credential for eol connection
Try { 
    $CredAzure = Get-AutomationPSCredential -Name $runbookcredential
}
        Catch {
            Write-Error "Failed to get credential!"
            Exit
        }   
Write-Output "Get automation credential - Success"

# connect eol
Try {
    Connect-ExchangeOnline -Credential $CredAzure
}
        Catch {    
            Write-Error "Failed to connect to MSOnline!"
            Exit
        }
Write-Output "Connect to EOL - Success"

# get default policy from org settings
Try {
    $defaultpolicy = Get-RetentionPolicy | Where-Object { $_.IsDefault -eq $true }
}
        Catch {    
            Write-Error "Failed to get default policy!"
            Exit
        }
Write-Output "Get default policy - Success"

# find enabled mailboxes with no policy set
Try {
    $mailboxes = Get-Mailbox -ResultSize Unlimited -Filter { ( RecipientTypeDetails -eq 'UserMailbox' ) -and ( ExchangeUserAccountControl -ne 'AccountDisabled') } | Where-Object { $_.RetentionPolicy -eq $null }
}
        Catch {    
            Write-Error "Failed to get mailboxes!"
            Exit
        }
Write-Output "Get mailboxes - Success"

# set to default policy
Try {
    foreach ($mailbox in $mailboxes) {
        Set-Mailbox -Identity $mailbox.UserPrincipalName -RetentionPolicy $defaultpolicy.Name
    }
}
        Catch {    
            Write-Error "Failed to set policy!"
            Exit
        }
Write-Output "Set default policy - Success"

# end