Create shared mailbox with same alias

A shared mailbox is a type of mail storage where you can have email addresses that all point to the same mailbox. This allows for easier collaboration and sharing between co-workers, friends or family members. It also helps keep your inbox cleaner by not having many accounts cluttering it up with emails from people you don’t need to be in touch with anymore.

The “create shared mailboxes with same alias at different domains in office 365” is a feature that allows users to create shared mailboxes with the same alias. The feature is available in Office 365.

When creating a new shared mailbox in the Microsoft 365 admin interface, an error notice appears stating that the email address is already in use by another mailbox. What is causing this problem, and what is the solution? In this post, we’ll look at how to set up a shared mailbox in a Microsoft 365 tenancy with the same alias.

Table of Contents

Introduction

In Microsoft 365, we have the domain alitajran.com, and we just added the domain spambull.com.

Microsoft creates the onmicrosoft.com domain by default.

The domains are as follows:

alitajran.com
alitajran.onmicrosoft.com
spambull.com

There is just one mailbox with an Exchange Online license active among the Active users: [email protected].

Because it is in use, the email address is not accessible.

We prefer to use the shared mailbox [email protected]. We do, however, receive the message:

Because “mailbox” uses the email address, it is not accessible.

Why do we get the notification that the email address is unavailable because it is already in use by another mailbox? Spambull.com is a separate domain from alitajran.com. According to our understanding, we should be permitted to use the email addresses [email protected] and [email protected].

Let’s have a look at PowerShell.

There is already a proxy address in use.

In PowerShell, let’s attempt to build a shared mailbox with the same alias but a different domain.

Connect to Exchange Online PowerShell by running PowerShell as an administrator.

Connect-ExchangeOnline (PS C:>)

Create a shared mailbox using the New-Mailbox cmdlet.

PS C:> New-Mailbox -Name “Info | SpamBull” -Alias “info” -Shared -PrimarySMTPAddress “[email protected]” PS C:> New-Mailbox -Name “Info | SpamBull” -Alias “info” -Shared -PrimarySMTPAddress “[email protected]” Proxy addresses or LegacyExchangeDN are already using the proxy address “SMTP:[email protected].” Please choose a different proxy address. + Information about the category: Not Specification: (0:Int32) [Server=VI1P195MB0301,RequestId=b9cf69d2-177a-475a-9474-558d955bd644,TimeStamp=03/11/2021 20:14:59], WLCDManagedMemberExistsException + FullyQualifiedErrorId: [Server=VI1P195MB0301,RequestId=b9cf69d2-177a-475a-9474-558d955 C9D7D671,Microsoft.Exchange.Management.RecipientTasks.NewMailbox + PSComputerName: outlook.office365.com [FailureCategory=Cmdlet-WLCDManagedMemberExistsException] C9D7D671,Microsoft.Exchange.Management.RecipientTasks.NewMailbox + PSComputerName: outlook.office365.com

The proxy address SMTP:[email protected] is already in use, according to the result. However, we used [email protected] as the main SMTP address rather than [email protected]. What’s going on?

How to set up a shared mailbox with the same alias

To avoid establishing a shared mailbox with the same alias, create a new shared mailbox with a different alias. Let’s have a look at it step by step to get a better idea.

Change the alias using the New-Mailbox cmdlet. We changed the alias from info to info2 in our example.

PS C:> New-Mailbox -Name “Info | SpamBull” -Alias “info2” -Shared -PrimarySMTPAddress “[email protected]” PS C:> New-Mailbox -Name “Info | SpamBull” -Alias “info2” -Shared -PrimarySMTPAddress “[email protected]” Name Database of Aliases ExternalDirectoryObjectId ProhibitSendQuota —————————————————————————————————————————————————————————————————————————————————— 6af3713c-1547-418a-b307-51dc784a0cc3 EURP195DG037-db182 EURP195DG037-db182 EURP195DG037-db182 EURP195DG037-db182 EURP195DG037-db182 EURP195DG037-db182 EURP195DG037-db182 EURP195DG037-db18

To access the information, use the Get-Mailbox cmdlet. The domain alitajran.com is shown as the UserPrincipalName, and the alias is info2.

Set the UserPrincipalName using the MicrosoftOnlineServicesID argument in the Set-Mailbox cmdlet.

Set-Mailbox PS C:> “-MicrosoftOnlineServicesID “[email protected]” -MicrosoftOnlineServicesID “[email protected]” -MicrosoftOnlineServicesID “[email protected] WARNING: UserPrincipalName “[email protected]” should match WindowsLiveID “[email protected],” and UserPrincipalName “[email protected]” should be retained “..

Make that the UserPrincipalName field has the right domain.

Consider adding the EmailAddresses option to the shared mailbox alias addresses. Learn more about how to use PowerShell to discover email addresses.

Get-Mailbox “Info | SpamBull” | select Name,Alias,UserPrincipalName,EmailAddresses PS C:> Get-Mailbox “Info | SpamBull” | select Name,Alias,UserPrincipalName,EmailAddresses —————————————————————————————————————————————————————————— info2 [email protected] | SpamBull SMTP:[email protected], SMTP:[email protected], SMTP:[email protected]

Remove any alias addresses with the alias name info2.

Set-Mailbox “Info | SpamBull” -EmailAddresses @remove=”[email protected]”,”[email protected]” PS C:> Set-Mailbox “Info | SpamBull” -EmailAddresses @remove=”[email protected]”,”[email protected]”

The shared mailbox will be verified in the last stage.

Check that the shared mailbox has the same alias.

In PowerShell, look at the shared mailbox.

PS C:> Get-Mailbox “Info | SpamBull” | select Name,Alias,UserPrincipalName,EmailAddresses Name,Alias,UserPrincipalName,EmailAddresses Name EmailAddresses Alias UserPrincipalName —————————————————————————————————————————————————————————— info2 [email protected] | SpamBull {SMTP:[email protected]}

In the Microsoft 365 admin center, check the shared mailbox.

The shared mailbox with the same alias is successfully formed. How did it go for you?

Continue reading: Using PowerShell, determine the capacity of a shared mailbox in Office 365 «

Conclusion

You now understand why the notice “email address not available because it is already in use” appears. The answer is to use Exchange Online PowerShell to generate the email address. Following that, you’ll see that the shared mailbox is available to use using the name you set.

Did you find this article to be interesting? You may also be interested in Increasing the mailbox size in Office 365. Don’t forget to subscribe to our newsletter and share this content.

The “add external user to shared mailbox” is a command that allows users to add an external user to a shared mailbox. This can be helpful if you want multiple people to have access to the same mailbox, but with different aliases.

{“@context”:”https://schema.org”,”@type”:”FAQPage”,”mainEntity”:[{“@type”:”Question”,”name”:”Can two mailboxes have the same alias?”,”acceptedAnswer”:{“@type”:”Answer”,”text”:”A: Yes, two mailboxes can have the same alias.”}},{“@type”:”Question”,”name”:”How many alias can a shared mailbox have?”,”acceptedAnswer”:{“@type”:”Answer”,”text”:”A: One alias per shared mailbox.”}},{“@type”:”Question”,”name”:”What is a shared mailbox alias?”,”acceptedAnswer”:{“@type”:”Answer”,”text”:”A: A shared mailbox alias is a security measure used to keep multiple users on the same Exchange server from having access to each others email. This maintains information confidentiality and data integrity of every user on an Exchange Server, limiting damage caused by system attacks or software glitches.”}}]}

Frequently Asked Questions

Can two mailboxes have the same alias?

A: Yes, two mailboxes can have the same alias.

How many alias can a shared mailbox have?

A: One alias per shared mailbox.

What is a shared mailbox alias?

A: A shared mailbox alias is a security measure used to keep multiple users on the same Exchange server from having access to each others email. This maintains information confidentiality and data integrity of every user on an Exchange Server, limiting damage caused by system attacks or software glitches.

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