Multiple domain distibution groups in one office 365

Question

At our company we run a few domains on our office 365, as such we want to have an "allusers" group for each domain, but for that I would really like a script that will go through all the users and check their domain name, and just make a simple
if statement to sort them. what i really need is the command that allows me to get their domain name or how to make a proper if statement that can handle the problem
thank you very much for your help
Beyir

Answer 1

here is another wierd question, i found a workaround, ill show you how my script is looking now (not complete)
$counter = 0
foreach ($Mailbox in Get-Mailbox -ResultSize Unlimited)
$string = $Mailbox.PrimarySmtpAddress
$string = get-User -identity pms
    Write-host "StringLength is: " $string.Length
Write-host $counter $Mailbox.PrimarySmtpAddress
$counter = $counter+1
I still need to change some stuff around, but what i really want to know is how to make the @mailbox.primarysmtpaddres into a string so i can compare them (need to compare length of email add to determine if it is a user or not)