How to get all users with alias as subdomain

Question

How to get all users with alias as subdomain

Mani 396

Hello All,

We need to pull a report where users having alias as our subdomains

We have around 20k users and we need to filter out them with our subdomains (15).

Please suggest a quick and easy to figure it out, pulling out the entire report and checking is consuming lot of time.

Example: Mani is having primary smtp with microsoft and alias with onmicrosoft, contoso

And i need to pull report for contoso from all 20k users.

Accepted answer

1 additional answer

Your answer

Answer 1

Alex Zhang-MSFT 6,620 Microsoft External Staff

Hello, @Mani,

Welcome to the Microsoft Q&A platform!

To efficiently pull a report of users with specific subdomain aliases, you can use PowerShell. Here's a script that can help you filter out users with the "contoso" subdomain from your 20k users:

1.Open PowerShell with administrative privileges.

2.Run the following script:

# Connect to Exchange Online
Connect-ExchangeOnline -UserPrincipalName ******@domain.com -ShowProgress $true

# Define the subdomain to filter
$subdomain = "contoso"

# Get all users and filter by alias
$users = Get-Mailbox -ResultSize Unlimited | Where-Object {
    $_.EmailAddresses -match $subdomain
}

# Export the filtered users to a CSV file
$users | Select-Object DisplayName, PrimarySmtpAddress, EmailAddresses | Export-Csv -Path "C:\Users\YourUsername\Documents\FilteredUsers.csv" -NoTypeInformation

# Disconnect from Exchange Online
Disconnect-ExchangeOnline -Confirm:$false

Test Results: User's image

This script should help you quickly generate the report you need without manually checking each user. Let me know if you need any further assistance!

If the answer is helpful, please click on “Accept answer” as it could help other members of the Microsoft Q&A community who have similar questions and are looking for solutions.

Thank you for your support and understanding.

Best Wishes,

Alex Zhang

Mani 396 Reputation points

2025-02-04T16:37:05.52+00:00

Hello @Alex Zhang-MSFT

Few of my users are having matching subdomain as alias, is there is anyway to pull that report (I need to pull report with 15 subdomains for around 20K users)

Example: ******@contoso.com, ******@ms.com, ******@domain.com

******@contoso.com, ******@ms.com, ******@domain.com

Alex Zhang-MSFT 6,620 Microsoft External Staff

Hello, @Mani,

Thank you for your prompt reply.

You can modify the PowerShell script to handle multiple subdomains. Here's an updated version that checks for any of the 15 subdomains in the aliases:

# Connect to Exchange Online
Connect-ExchangeOnline -UserPrincipalName ******@domain.com -ShowProgress $true

# Define the subdomains to filter
$subdomains = @("contoso", "ms", "domain", "subdomain4", "subdomain5", "subdomain6", "subdomain7", "subdomain8", "subdomain9", "subdomain10", "subdomain11", "subdomain12", "subdomain13", "subdomain14", "subdomain15")

# Get all users and filter by alias
$users = Get-Mailbox -ResultSize Unlimited | Where-Object {
    $match = $false
    foreach ($subdomain in $subdomains) {
        if ($_.EmailAddresses -match $subdomain) {
            $match = $true
            break
        }
    }
    $match
}

# Export the filtered users to a CSV file
$users | Select-Object DisplayName, PrimarySmtpAddress, EmailAddresses | Export-Csv -Path "C:\Users\YourUsername\Documents\FilteredUsers.csv" -NoTypeInformation

# Disconnect from Exchange Online
Disconnect-ExchangeOnline -Confirm:$false

This script will help you generate a report for users with any of the specified subdomains in their aliases. Let me know if you need any further assistance!

If the answer is helpful, please click on “Accept answer” as it could help other members of the Microsoft Q&A community who have similar questions and are looking for solutions.

Thank you for your support and understanding.

Best Wishes,

Alex Zhang

Mani 396 Reputation points

2025-02-05T15:26:22.8933333+00:00

Hello @Alex Zhang-MSFT ,

Thanks for your quick response,

I will try this and update you.
Mani 396 Reputation points

2025-02-05T17:54:32.96+00:00

Hello @Alex Zhang-MSFT ,

I tried your suggestion and it got the results and i need one more condition to add,

Any chance to get only the mentioned subdomains as alias

As of the above command returned all alias of the users having

Alex Zhang-MSFT 6,620 Microsoft External Staff

Hello, @Mani,

Thank you for your reply.

Sure, you can modify the script to include only the specified subdomains in the aliases. Here's an updated version of the script:

# Connect to Exchange Online
Connect-ExchangeOnline -UserPrincipalName ******@domain.com -ShowProgress $true

# Define the subdomains to filter
$subdomains = @("contoso", "ms", "domain", "subdomain4", "subdomain5", "subdomain6", "subdomain7", "subdomain8", "subdomain9", "subdomain10", "subdomain11", "subdomain12", "subdomain13", "subdomain14", "subdomain15")

# Get all users and filter by alias
$users = Get-Mailbox -ResultSize Unlimited | Where-Object {
    $match = $false
    foreach ($subdomain in $subdomains) {
        if ($_.EmailAddresses -match $subdomain) {
            $match = $true
            break
        }
    }
    $match
}

# Filter only the specified subdomains in the aliases
$filteredUsers = $users | ForEach-Object {
    $user = $_
    $filteredAliases = @()
    foreach ($alias in $user.EmailAddresses) {
        foreach ($subdomain in $subdomains) {
            if ($alias -match $subdomain) {
                $filteredAliases += $alias
                break
            }
        }
    }
    [PSCustomObject]@{
        DisplayName = $user.DisplayName
        PrimarySmtpAddress = $user.PrimarySmtpAddress
        EmailAddresses = $filteredAliases -join "; "
    }
}

# Export the filtered users to a CSV file
$filteredUsers | Export-Csv -Path "C:\Users\YourUsername\Documents\FilteredUsers.csv" -NoTypeInformation

# Disconnect from Exchange Online
Disconnect-ExchangeOnline -Confirm:$false

This script will ensure that only the specified subdomains are included in the aliases in your report. Let me know if you need any further adjustments!

If the answer is helpful, please click on “Accept answer” as it could help other members of the Microsoft Q&A community who have similar questions and are looking for solutions.

Thank you for your support and understanding.

Best Wishes,

Alex Zhang

Kory Skarbek 0 Reputation points

2025-03-06T18:07:24.5066667+00:00

Is there a way to exclude unlicensed users?
Kory Skarbek 0 Reputation points

2025-03-10T18:18:26.0166667+00:00

Is there a cleaner way to see all email addresses? I don't need to see SIP, SMTP, etc. I only want to see users, user's main email, and any aliases they have.

Answer 2

Vasil Michev 115.7K MVP

You can use server-side filtering for that. For example, to list all recipients associated with the .onmicrosoft.com domain, you can do this:

Get-Recipient -RecipientPreviewFilter {EmailAddresses -like "*@tenant.onmicrosoft.com"}

If you only care about mailboxes, use Get-Mailbox with the -Filter parameter instead.

Mani 396 Reputation points

2025-02-04T16:36:20.7233333+00:00

Few of my users are having matching subdomain as alias, is there is a way to pull that report (I need to pull report with 15 subdomains for around 20K users)

Example: ******@contoso.com, ******@ms.com, ******@domain.com

******@contoso.com, ******@ms.com, ******@domain.com

Get-Recipient -RecipientPreviewFilter {EmailAddresses -like "*@tenant.onmicrosoft.com", *@tenant.com}

Share via

How to get all users with alias as subdomain

1 additional answer

Your answer