question

Hi,

You can use powershell Az module to create a powershell script.

Get-AzADUser will give you all users in a particular tenant and then you can compare in whatever way you want.

Hope this helps

@MattHolko-0316

Connect to the purchased tenant, run commands below on it(Those two files will be used to compare on the new tenant):

 Get-Mailbox -RecipientTypeDetails UserMailbox -ResultSize unlimited | select PrimarySmtpAddress |  Export-Csv c:/temp/users.csv -NoTypeInformation
    
 Get-DistributionGroup -ResultSize unlimited | select PrimarySmtpAddress |  Export-Csv c:/temp/groups.csv -NoTypeInformation

Connect to new tenant, then run script below on it(Save script blow into a .PS1 file):
Compare mailboxes:

 $users = Import-Csv c:/temp/users.csv
    
 foreach ($user in $users){
     $temp = $user.PrimarySmtpAddress.Split('@')[0]
     If(Get-Mailbox $temp -erroraction 'silentlycontinue'){
         Write-Host $temp "exist in this tenant"
     }
 }

Compare groups:

 $users = Import-Csv c:/temp/Groups.csv
    
 foreach ($user in $users){
     $temp = $user.PrimarySmtpAddress.Split('@')[0]
     If(Get-DistributionGroup  $temp -erroraction 'silentlycontinue'){
         Write-Host $temp "exist in this tenant"
     }
 }

If there exist a mailbox or group using the same prefix for email address, you will get a result like below:

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