Tech Blog

As I mentioned in another post, you can force a EoL mailbox to take on a SMTP with this command:

Set-Mailbox User.Name -WindowsEmailAddress User.Name@Bohemiangrove.co.uk

But occasionally it won’t work:

The proxy address "SMTP:User.Name@Bohemiangrove.co.uk" is already being used by the proxy addresses or LegacyExchangeDN of "User.Name_bohemiangrove.co.uk#EXT#". Please choose another proxy address.

    + CategoryInfo          : NotSpecified: (Adri Donkers:ADObjectId) [Set-Mailbox], ProxyAddressExistsException

    + FullyQualifiedErrorId : [Server=VI1PR04MB4349,RequestId=8938a92c-006d-4f9f-b230-937f591d20e4,TimeStamp=22/10

   /2018 06:18:53] [FailureCategory=Cmdlet-ProxyAddressExistsException] 169E5E0,Microsoft.Exchange.Management.Rec 

  ipientTasks.SetMailbox

    + PSComputerName        : ps.outlook.com

So to find who’s using the address you can search all of Azure using:

Get-Recipient | where {$_.EmailAddresses -match "User.Name@Bohemiangrove.co.uk"} | fL Name, RecipientType,emailaddresses