How to Check SMTP AUTH is Enabled

 

How to Check SMTP AUTH is Enabled or Disabled in Microsoft 365

Disable or Enable SMTP AUTH in your organization

Note: You can only disable (or enable) SMTP AUTH globally for your organization by using Exchange Online PowerShell.

1. Connect to Exchange Online PowerShell or you can open Windows PowerShell (Admin) then run below commands:

Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope LocalMachine -Force;
Install-PackageProvider -Name NuGet -Force;
Set-PSRepository -Name "PSGallery" -InstallationPolicy Trusted;
Install-Module -Name ExchangeOnlineManagement;
Import-Module ExchangeOnlineManagement;
Connect-ExchangeOnline;

2. Run the following command to check SMTP AUTH status:

Get-TransportConfig | Format-List SmtpClientAuthenticationDisabled

SmtpClientAuthenticationDisabled property is True means the SMTP AUTH is already disabled

PS C:\> Get-TransportConfig | Format-List SmtpClientAuthenticationDisabled

SmtpClientAuthenticationDisabled : True
 

3. Run the following command to enable SMTP AUTH:

Set-TransportConfig -SmtpClientAuthenticationDisabled $false

Note: To disable SMTP AUTH if it’s already enabled, use the value $true.

 

Enable SMTP AUTH for specific mailboxes

Microsoft highly recommend that you disable SMTP AUTH in your Exchange Online organization, and enable it only for the accounts (that is, mailboxes) that still require it.

Note: You must disable Security Defaults in Azure Active Directory, when it enabled, it’ll disable basic authentication in whole tenant and it overwrites all others settings. It means enable SMTP AUTH for specific mailboxes will not work.

Set-CASMailbox -Identity maria@leoguides.me -SmtpClientAuthenticationDisabled $false

To verify that you’ve enabled or disabled SMTP AUTH for a specific mailbox, you can check it through Microsoft admin center or using PowerShell.

Individual mailboxes in the Microsoft 365 admin center: Go to Users > Active users > select the user > click Mail > click Manage email apps and verify the value of Authenticated SMTP (checked = enabled, unchecked = disabled).

Or you can using the following command with SmtpClientAuthenticationDisabled property (False = enabled, True = disabled, blank = use organization setting).

PS C:\> Get-CASMailbox -Identity maria@leoguides.me  | Format-List SmtpClientAuthenticationDisabled

SmtpClientAuthenticationDisabled : False
 

All mailboxes where SMTP AUTH is enabled: Run the following command:

$Users = Get-CASMailbox -ResultSize unlimited
$Users | where {$_.SmtpClientAuthenticationDisabled -eq $false} | Select-Object DisplayName,PrimarySmtpAddress

PS C:\> $Users | where {$_.SmtpClientAuthenticationDisabled -eq $false} | Select-Object DisplayName,PrimarySmtpAddress

DisplayName PrimarySmtpAddress
----------- ------------------
Chris       chris@leoguides.me
Maria       maria@leoguides.me

All mailboxes where SMTP AUTH is controlled by the organization setting: Run the following command:

$Users = Get-CASMailbox -ResultSize unlimited
$Users | where {$_.SmtpClientAuthenticationDisabled -eq $null} | Select-Object DisplayName,PrimarySmtpAddress

PS C:\> $Users = Get-CASMailbox -ResultSize unlimited
PS C:\> $Users | where {$_.SmtpClientAuthenticationDisabled -eq $null} | Select-Object DisplayName,PrimarySmtpAddress

DisplayName              PrimarySmtpAddress
-----------              ------------------
Bon Ben                  admin@bbguides.onmicrosoft.com
Anna                     anna@leoguides.me
Tom                      tom@leoguides.me
Tonny                    tonny@leoguides.me