Script to Remove Old Domains from User Email Addresses

When managing email addresses and domains in Exchange Server, old email addresses are never removed automatically. This is good because it ensures that email addresses on a mailbox are never accidentally lost. However, you may want to clean up old domains or address formats that are no longer in use.

Some common scenarios where you might want to remove an old domain:

• An SMB deployment of Exchange Server where a .local domain was added as the first domain for email addresses.
• Old GroupWise addresses are left in place from an older migration.
• Obsolete domain left over from a company merger many years ago

I often find that obsolete domains are identified when I run IDFix as part of preparing to migrate to Office 365. To simplify the removal of obsolete domains, I have created the following script.

A few things to note:

• You need to set $RemovePattern to identify the domain to be removed. Any email addresses matching this pattern will be removed from proxyAddresses attribute in Active Directory objects.
• The script uses Get-ADObject rather than Get-ADUser to make sure that the domain is removed from distribution groups too.
• This version of the script is capable of removing multiple instances of a matching email address. So, if a user has several email addresses in the old domain, all of them are removed.
• At the end of the script, I use Write-Progress to display a status bar. It's not necessary, but if there is a large number of users it's nice to see activity on the screen instead of just waiting and hoping it's doing something.

 #This pattern is used to match the email addresses being removed.  
 #Test that this pattern finds the correct users and email addresses  
 #before running this script.  
 #Example: $pattern = "smtp:*@olddomain.com"  
 $RemovePattern = "smtp:*@olddomain.local"  
   
 Import-Module ActiveDirectory #only required for 2008 R2  
   
 #Get the users that have an email address that matches the pattern  
 Clear-Host  
 Write-Host "Querying objects...This may take a moment"  
 Write-Host ""  
 $objects = Get-ADObject -Filter {ProxyAddresses -like $RemovePattern} -Properties ProxyAddresses  
   
 #Identify address being removed from first user for warning  
 [String]$proxyexample = $objects[0].proxyaddresses -like $RemovePattern  
   
 #Display warning and get confirmation  
 Write-Host "You are going to remove email addresses that match the following pattern:"  
 Write-Host -ForegroundColor Red "$RemovePattern"  
 Write-Host ""  
 Write-Host "This is an example from the first object:"  
 Write-Host -ForegroundColor Red "$proxyexample"  
 Write-Host ""  
 Write-Host "This will modify $($objects.count) objects"  
 Write-Host ""  
   
 $confirm = Read-Host "Enter Y to continue"  
 If ($confirm -ne "Y") {Break}  
   
 #Prepare variables for processing status  
 $total = $objects.count  
 $current = 0  
   
 #Processing users to remove addresses  
 Foreach ($o in $objects) {  
     
   #Build list of addresses to remove for object  
   #required because there might be multiple that match  
   $proxy= New-Object System.Collections.ArrayList  
   
   Foreach ($a in ($o.ProxyAddresses)) {  
     If ($a -like $RemovePattern) {  
       $proxy.add($a) | Out-Null  
     } #end if  
   } #end foreach  
     
   #Remove each bad address  
   Foreach ($p in $proxy) {  
     Set-ADObject $o -Remove @{'proxyAddresses'=$p}  
   }  
     
   #Pause  
   
   #Processing status  
   $current += 1  
   Write-Progress -Activity "Removing email addresses that match pattern" -Status "Progress: $current" -PercentComplete ($current/$total*100)   
 } #end foreach