The proxy address "SMTP:.onmicrosoft.com" is already being used by the proxy addresses or LegacyExchangeDN. Please choose another proxy address.

Question

Hello,

I am trying to create a shared mailbox ******@domain1.com in Exchange online but getting error The proxy address is already being used by the proxy addresses or LegacyExchangeDN. Please choose another proxy address.

I have another shared mailbox with same same but different domain ******@domai2.com.

How can I resolve this?

Answer 1

Hi @Bhavneesh Sohal

There is a Microsoft documentation about this error message: Error when creating shared mailboxes

If you see the error message, The proxy address "smtp:<shared mailbox name>" is already being used by the proxy addresses or LegacyExchangeDN of "<name>". Please choose another proxy address, it means you're trying to give the shared mailbox a name that's already in use. For example, let's say you want shared mailboxes named info@domain1 and info@domain2. There are two ways to do this:

• Use Exchange Online PowerShell. See this blog post for instructions: Create Shared Mailboxes with Same Alias at Different Domains
• Name the second shared mailbox something different from the start to get around the error. Then in the admin center, rename the shared mailbox to what you want it to be.

Please follow the solutions to either use Exchange Online Powershell or use another alias.

---

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment". 

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.