If you would like to segment users in your Office 365 subscription or on your Exchange On-Premise you will need to use Address Book Policy.

This set of cmdlets will create everything you need to start using Address Book Policy in Office 365 or Exchange On-Premise. Keep in mind that prior running this cmdlets you should already set the value of CustomAttribute1 on each mailbox (PowerShell or via Exchange Admin Center).

If you are not familiar with Address Book Policy, I would recommend checking Microsoft TechNet first – this script is just a Cheat Sheet so you don’t need to create your own. 

#Connect to Exchange Online
$UserCredential = Get-Credential
$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/ -Credential $UserCredential -Authentication Basic -AllowRedirection
Import-PSSession $Session -DisableNameChecking

#Set CustomAttribute1 value (modify this value as needed)
$CustomAttribute1 = "contoso.com"

#Create new Address Lists
New-AddressList -Name $CustomAttribute1 -RecipientFilter {((RecipientType -eq 'UserMailbox') -or (RecipientType -eq "MailUniversalDistributionGroup") -or (RecipientType -eq "DynamicDistributionGroup")) -and (CustomAttribute1 -eq $CustomAttribute1)}
New-AddressList -Name "$CustomAttribute1 Rooms" -RecipientFilter {(Alias -ne $null) -and (CustomAttribute1 -eq $CustomAttribute1) -and ((RecipientDisplayType -eq 'ConferenceRoomMailbox') -or (RecipientDisplayType -eq 'SyncedConferenceRoomMailbox'))}
#Create Global Address List
New-GlobalAddressList -Name "$CustomAttribute1 GAL" -RecipientFilter {(CustomAttribute1 -eq $CustomAttribute1)}
#Create Offline Address Book
New-OfflineAddressBook -Name "$CustomAttribute1 OAB" -AddressLists "$CustomAttribute1 GAL"
#Create Address Book Policy
New-AddressBookPolicy -Name "$CustomAttribute1 ABP" -AddressLists $CustomAttribute1 -OfflineAddressBook "\$CustomAttribute1 OAB"  -GlobalAddressList "\$CustomAttribute1 GAL" -RoomList "\$CustomAttribute1 Rooms"
#Assign Address Book Policy to Mailboxe's with CustomAttribute1 value equal to variable $CustomAttribute1
Get-Mailbox -resultsize unlimited | where {$_.CustomAttribute1 -eq "$CustomAttribute1"} | Set-Mailbox -AddressBookPolicy "$CustomAttribute1 ABP"
#List all Mailboxe's
Get-Mailbox -ResultSize unlimited | select name,addressbookpolicy,customattribute1

#Exit Exchange Online Session
Remove-PSSession $Session

This example will create an Address Book Policy linked to a dedicated Address Lists, Global Address List and Offline Address Book. ABP will be assigned to all Mailboxe’s with CustomAttribute1 equal to variable $CustomAttribute1 (in this example contoso.com). Modify the $CustomAttribute1 variable as needed with any value (I personally use domain names). Rerun the cmdlet’s multiple times to create different Address Book Policies.

The cmdlets works also with Exchange On-Premise, just don’t use the #Connect to Exchange Online and #Exit Exchange Online Session section.