Shadow Mailbox Deletion

https://techcommunity.microsoft.com/t5/exchange-team-blog/permanently-clear-previous-mailbox-info/ba-p/607619

Exchange Online PowerShell

Connect-EXOPSSession -UserPrincipalName admin@contoso.com

1. Get-User jon@contoso.com | Select name,*Recipient*

2. Set-User jon@contoso.com -PermanentlyClearPreviousMailboxInfo

Connect to Exchange Online PowerShell

https://docs.microsoft.com/en-us/powershell/exchange/exchange-online/connect-to-exchange-online-powershell/connect-to-exchange-online-powershell?view=exchange-ps

$UserCredential = Get-Credential

$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/ -Credential $UserCredential -Authentication Basic -AllowRedirection

Import-PSSession $Session -DisableNameChecking

Remove-PSSession $Session