unable to create unified group

Question

Hi all,

I am trying to create a unified group in PowerShell using the New-UnifiedGroup cmdlet, but I am encountering the error below:

Write-ErrorMessage : |Microsoft.Exchange.Configuration.ObjectModel.ProxyAddressExistsException|The proxy address "SMTP:ug1@contoso.com" is already being used by the proxy addresses or LegacyExchangeDN or 
UserPrincipalName of "UG1". Please choose another proxy address.

I checked the Exchange Admin Center (shared mailboxes, distribution lists, dynamic distribution lists, and mail-enabled security groups), but I could not find this address. It might be an additional email address. Can someone guide me on how to trace this?

Answer 1

Hi @Glenn Maxwell ,

Welcome to the Microsoft Q&A platform!

Based on your description, you are dealing with a proxy address conflict. This can happen if the SMTP address is already in use by another mail-enabled object in your organization. Here are some steps you can take to track down and resolve this issue:

1. Connect to Exchange Online PowerShell:

Connect-ExchangeOnline -UserPrincipalName <your UPN>

2. Run the following command to list all mail recipients using the conflicting SMTP address:

Get-EXORecipient -ResultSize Unlimited | Where-Object {$_.EmailAddresses -match "SMTP:ug1@contoso.com"} | fl Name, RecipientType, EmailAddresses

3. If you don't know the exact SMTP address, you can search for a partial match:

Get-EXORecipient -ResultSize Unlimited | Where-Object {$_.EmailAddresses -match "ug1@contoso.com"} | fl Name, RecipientType, EmailAddresses

4. Once you identify the object causing the conflict, you can remove or change the conflicting proxy address. For example, if the object is a mail-enabled public folder, you can disable it using the following command:

Get-MailPublicFolder -ResultSize Unlimited | Where-Object {$_.EmailAddresses -match "SMTP:ug1@contoso.com"} | Disable-MailPublicFolder

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Please feel free to contact me for any updates. And if this helps, don't forget to mark it as an answer.

Best,

Jake Zhang

Answer 2

You can use this PowerShell script to find all the primary addresses and alias addresses in your organization. https://m365scripts.com/exchange-online/get-all-office-365-email-address-and-alias-using-powershell/

After generating the report, you can check whether the specific address is already in use.