In users' e-mail addresses, remove all references to a domain - powershell

Question

On our cloud-hosted O365 tenancy, I would like to run a PowerShell script which looks at every user and removes any reference to an e-mail domain I'm trying to get rid of.
As an example, if we have the following user:
Jimbob Goodemails
Jimbob.Goodemails#newdomain.com
Jimbob.Goodemails#olddomain.com
Jimbob.Goodemails#domain.onmicrosoft.com (the default O365 domain)
I would like to remove #olddomain.com addresses (in the above case, Jimbob.Goodemails#olddomain.com) from every user.
On most of these accounts, that domain will be set up as an alias - e.g. smtp:Jimbob.Goodemails#olddomain.com in the proxyAddresses field.
However, some users (far fewer, perhaps only 3 or 4) may have it as their main e-mail address (e.g. SMTP:Jimbob.Goodemails#olddomain.com in proxyAddresses but also as the mail and UPN attributes). These users can just use the default O365 e-mail address instead.
I have tried the following script, to no avail:
foreach($i in Get-Mailbox -ResultSize Unlimited) {
　 $i.EmailAddresses |
　　　 ?{$_.AddressString -like '*#olddomain.com'} | %{
　　　　　 Set-Mailbox $i -EmailAddresses #{remove=$_}
　　　 }
}
It sits for a while, then appears to finish, but nothing has changed.
I have used an Active Directory PowerShell script which does this for my AD-synchronised users, so I'm primarily looking to change Cloud users and groups.
It would also be useful to know how to search for such users too.

Answer 1

The Method:
Create an Array of your Current SMTP's:
$SMTPs = $Mailbox.EmailAddresses -split ","
Remove the Unwanted SMTP Addresses:
$SMTPs | ? {$_ -notmatch 'olddomain.com'}
Then Update The Mailbox with the filtered SMTPs:
Set-Mailbox $Mailbox -EmailAddresses $SMTPs
In your Example:
foreach ($i in Get-Mailbox -ResultSize Unlimited)
{
$SMTPs = $i.EmailAddresses -split "," | ? {$_ -notmatch 'olddomain.com'}
Set-Mailbox $i -EmailAddresses $SMTPs
}