Add-PSSnapin Microsoft.Exchange.Management.PowerShell.E2010 $ADSearchBase = "ou=Firmenname,dc=domain,dc=tld" $domain = "domain.tld" #Users $targets = get-aduser -filter {Enabled -eq $true} -searchbase $ADSearchBase foreach ($user in $targets) { $mbxalias = (get-mailbox -identity $user.SamAccountName).Alias Set-ADUser $user -add @{proxyaddresses="smtp:$mbxalias@$domain"} } #Distribution Groups $grouptargets = get-adgroup -filter "groupcategory -eq 'distribution'" -searchbase $ADSearchBase foreach ($group in $grouptargets) { $mbxalias = (get-distributiongroup -identity $group.SamAccountName).Alias Set-ADGroup $group -add @{proxyaddresses="smtp:$mbxalias@$domain"} } #Dynamic Distribution Groups $dyngrouptargets = get-adobject -filter "objectclass -eq 'msExchDynamicDistributionList'" -searchbase $ADSearchBase foreach ($dyngroup in $dyngrouptargets) { $mbxalias = (get-dynamicdistributiongroup -identity $dyngroup.Name).Alias Set-ADObject $dyngroup -add @{proxyaddresses="smtp:$mbxalias@$domain"} }