Powershell Exchange retention Policy

$NeedsRetentions = @()
# Get Start Time for script timer
$startDTM = (Get-Date)

#Authenticate using cached credentials or re-prompt for credentials.
if (Test-Path C:\temp\mycred.xml) {
    $UserCredential = Import-CliXML C:\temp\mycred.xml}
else{
    Get-Credential | Export-CliXml C:\temp\mycred.xml
    $UserCredential = Import-CliXML C:\temp\mycred.xml}

#Connect to Exchange Server
$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri http://munprdcasht04.exchange.com/PowerShell/ -Authentication Kerberos -Credential $UserCredential
Import-PSSession $Session

#returns alias' for mailboxes where creation date is <= 7 days and
#resides on "ABC" or "DEF" server and has no retention policy applied
$NeedsRetentions = (Get-Mailbox -ResultSize Unlimited| Where-Object {
($_.WhenCreated –ge ((Get-Date).Adddays(-7))) -and
(($_.ServerName -like "*munprdmbxa*") -or ($_.ServerName -like "*wauprdexa*")) -and
($_.retentionpolicy -ne "PurgeDeletedItemsFolder_60days")} |
ft -auto alias)

ForEach ($NeedsRetention in $NeedsRetentions){
    set-mailbox -Identity $NeedsRetention -RetentionPolicy "PurgeDeletedItemsFolder_60days"
    }

# Get End Time
$endDTM = (Get-Date)

# Echo Time elapsed
"Elapsed Time: $(($endDTM-$startDTM).totalseconds) seconds"