Hello,

Our exchange server is hosted through Office 365.

I was attempting to add an "other email address" to one of our users (we'll call him "User 1") when I encountered the following error:

The proxy address "smtp:sales@[domain].com" is already being used by the proxy addresses or LegacyExchangeDN of "[User 2]". Please choose another proxy address. (The "MailUniversalDistributionGroup" with display name "[User 2]" is already setup and using the same address.)

"User 2" doesn't exist anymore though... Or rather, that user doesn't appear in my list of "Active Users" on my Office 365 Admin dashboard.

So... how do I overcome this issue?

• Edited by thefanw00t Thursday, March 26, 2015 9:30 PM

Hi,

From your description, it seems that the address sales@[domain].com has been used in another mailbox. I recommend you use the following cmdlet to find out which mailbox is using this address.

Get-recipient | Where {$_.EmailAddresses -match "sales@domain.com"} | select Identity, DisplayName, RecipientType. The mailbox which is using this address will show up in the result.

Hope this can be helpful to you.

Best regards,