Forwarding for Entra ID users without licenses

Question

I have a contoso.com domain registered as an Accepted Domain in Exchange Online. I also have bunch of users in Entra ID (formally AAD) registered with their respective contoso.com UPN. I need to set up redirection for those users, so if someone sends an email to ******@contoso.com, a user would get it to his real email address (i.e. ******@corpo.com - located in another tenant). I tried to create a mail user with the existing UPN address, but got a message saying

"Mail user creation failed!
The proxy address "SMTP:*****@contoso.com" is already being used by the proxy addresses or LegacyExchangeDN. Please choose another proxy address."*

I didn't find the way I can remove proxy address from the user. I thought I can use a shared mailbox to create a redirection, but in that case I need to disable the actual users, which is not suitable in my case as they have been used for third party apps. Is there any other way I can set up redirection?

Answer 1

Hi @Alex Rough

What is the current user type of this user ******@contoso.com?

You can use the following cmdlet in Exchange Online Powershell to check:

Get-Recipient -identity ******@contoso.com | fl RecipientTypeDetails

If it is usermailbox, you can either create a mail flow rule (Exchange/server side method) or an Outlook inbox rule (Outlook/client side method) to redirect the message to ******@corpo.com.

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Mail flow rule:

Outlook inbox rule:

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If it is not a usermailbox, the mail flow rule method should still work for you in this case.

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Answer 2

I found a solution. I just create a shared mailbox and setup forwarding there.

Answer 3

Hi @Alex Rough

Glad to hear you have found a solution.

While since Microsoft Q&A forum has a policy that "The question author cannot accept their own answer. They can only accept answers by others", I'll repost your solution in case you'd like to "Accept" the answer : )

[Forwarding for Entra ID users without licenses]

Scenario:

Need to setup email forwarding from ******@contoso.com (current tenant) to ******@corpo.com (external tenant) when ******@contoso.com does not have a mailbox.

Solution:

Create shared mailboxes with the email address and setup forwarding on the shared mailboxes.