Bulk change all O365 email addresses

Question

Hi,
got forwarded from http://community.office365.com/en-us/f/155/p/273731/836967.aspx#836967 to this forum.
To make it short: I need to remove all of my Office 365 domains from the current tenant, even though they might still be in use for userprincipalname, emailaddresses or primarysmtpaddress. Mostly we're talking about MailUser-objects. 
The goal is to change all of the above values to [email protected] .
I already tried several scripts - some were outdated, some were not working for Office 365.  The only one which (particularly) worked out was this one:
get-mailuser -resultsize unlimited | foreach { set-mailuser -identity $_.identity -emailaddresses "SMTP:$($_.primarysmtpaddress)"}
Does anyone have any idea on how to solve this?
Best,
Daniel

Answer 1

To list all mailboxes that have aliases matching a particular domain, use the following:
$allm = Get-Mailbox -Filter {Emailaddresses -like "*@domain.com"}
To change the aliases, use this:
$allm | % { Set-Mailbox $_.Identity -EmailAddresses $_.Emailaddresses.Replace("domain.com","domain.onmicrosoft.com") }
And repeat the same for contacts, mail users, etc. Note that you will need to REMOVE the @domain.onmicrosoft.com address first, if it is already added on those objects.
To do the same for the UPNs, use this:
$all = Get-MsolUser -all
$all | ? {$_.UserPrincipalName -like "*@domain.com"} | % { Set-MsolUserPrincipalName -UserPrincipalName $_.UserPrincipalName -NewUserPrincipalName $_.UserPrincipalName.Replace("domain.com","domain.onmicrosoft.com") }