Office 365 – Block Basic Authentication

Microsoft recently announced they will disable basic authentication for all M365 tenants. This deadline has been pushed postponed due to the impact of COVID-19 across the globe.

Latest update: The latest from Microsoft is, effective October 1, 2022 Basic authentication will be disabled in all tenants.

The following components of Exchange Online will be affected,

  • Exchange Web Services(EWS)
  • POP
  • IMAP
  • Exchange ActiveSync
  • Remote PowerShell

Why is this a big deal?

Basic authentication uses username and password for client access requests. This used to be the industry standard during the time which organizations didn’t understand the cost of security breaches. It poses a significant security risk as Business Email Compromise (BEC) scams have exposed organizations to billions of dollars in potential losses. Check out this 2019 report from ProofPoint that goes into details.

Disabling Basic Authentication will help protect Exchange Online from brute force or password spray attacks. As the above mentioned report goes into, IMAP-based password-spraying campaigns are very effective in particular.

Beyond all this, Basic Authentication doesn’t enforce MFA and this should be the biggest driver for organizations to move away from it.

Is Basic Authentication enabled in your tenant?

Here is how to check if Basic Authentication is enabled in your tenant,

Screenshot above shows how to check if ‘Basic Auth’ is enabled in tenant

Determine who is using Basic Authentication in your tenant

Before you turn off basic authentication for protocols, view your sign-in reports in the ‎Azure AD‎ portal to determine who is using it in your organization.

This can be determined using sign-in logs in Azure AD.

In your Azure AD admin center, Click the ‘Sign-in logs’ blade.,

  • Select ‘Last 1 month‘ in the Date
  • Add a ‘Client app‘ as a second filter, choose all options under the ‘Legacy Authentication Clients‘ and click ‘Apply
Azure AD sign-ins | Basic Auth filter

With this report information, you can contact the application and account owners to determine why Basic Authentication is still in use. This information will also come in handy later if you are planning to allow exceptions to these accounts/applications. I’ve covered it later in this post.

Disable Basic Authentication

Before you begin,

  • Verify Modern Authentication is enabled
  • Verify your email clients are Modern Authentication capable

In this post, I’ve elaborated how to block Basic Authentication using Azure AD conditional access.

IMO, the easiest method to disable Basic Authentication is to use authentication policies.

With Authentication policies you can,

  • Apply a default organization level policy that blocks Basic Authentication
  • Apply a per user policy to allow certain protocols. Example: ActiveSync

Create Authentication Policy

This creates an authentication policy named ‘Block Basic Auth’

New-AuthenticationPolicy -Name "Block Basic Auth"

When you create a new authentication policy without specifying any protocols, Basic Authentication is blocked for all client protocols in Exchange Online.

The default value of the AllowBasicAuth* parameters (switches) is False for all protocols.

Set Default Authentication Policy

The default policy is assigned to all users in the tenant who don’t have a specific policy assigned to them. To configure the default authentication policy for the organization, use this:

Set-OrganizationConfig -DefaultAuthenticationPolicy "Block Basic Auth"

To verify that a default authentication policy is configured,

Get-OrganizationConfig | Format-Table DefaultAuthenticationPolicy

Create user specific authentication policies

Authentication policies assigned to users take precedence over the default organization policy.

  • To enable Basic authentication for a specific protocol that’s disabled, specify the switch without a value
  • To disable Basic authentication for a specific protocol that’s enabled, use the value :$false

In this scenario, I’m creating an authentication policy to allow ActiveSync. This is sometimes typical in organizations where users will have Intune managed devices but would like to add second O365 email from a different tenant. The Outlook app prevents this but the built-in mail app can be used with ActiveSync to fetch email.

New-AuthenticationPolicy -Name "Allow ActiveSync" -AllowBasicAuthActiveSync
New policy to allow ActiveSync

This example assigns the policy named ‘Allow ActiveSync’ to the user account ‘JoniS’

$Id = Read-Host "Enter user's email address"
Set-User -Identity $Id -AuthenticationPolicy "Allow ActiveSync"

To confirm the policy is assigned,

Get-User -Identity $Id | fl AuthenticationPolicy
Assign policy to user and confirm assignment

To assign a policy to a list of users, fill text file with the user’s UPN one per line.,

$LM = Get-Content "C:\Scripts\AllowAuthActiveSync.txt"
$LM | foreach {Set-User -Identity $_ -AuthenticationPolicy "Allow ActiveSync"}

To get all users assigned to a policy you need to get the policy’s DN using the cmdlet Get-AuthenticationPolicy,

$PolicyId = Read-Host "Enter policy ID in distinguished name format"
Get-User -Filter "AuthenticationPolicy -eq '$PolicyId'"
Assign policy to user, confirm and get all users assigned to a policy
Determine policy DN using ‘Get-AuthenticationPolicy’

By default, when you create or change the authentication policy assignment on users or update the policy, the changes take effect within 24 hours. If you want the policy to take effect within 30 minutes, use the following syntax:

$Id = Read-Host "Enter user's email address"
Set-User -Identity $Id -STSRefreshTokensValidFrom $([System.DateTime]::UtcNow)

This example below immediately applies the authentication policy to multiple users. As I’m in the same PowerShell session and haven’t changed the variables you used to identify the users,

$LM | foreach {Set-User -Identity $_ -STSRefreshTokensValidFrom $([System.DateTime]::UtcNow)}

Depending on your organizational requirement, you can create additional authentication policies allowing other protocols and assigning it to users.

And it’s highly recommended to keep track of these users and eventually remove these exceptions.

Thank you for stopping by. ✌

Office 365 – Plus Addressing – Updated

What is Plus addressing?

Plus addressing or subaddressing is available in Exchange Online. Plus addressing is using a unique, dynamically created receive-only email addresses for mailboxes.

  • Basic syntax of an SMTP email address: @. Example,
  • Plus addressing syntax: +@. Example,

The original email address must be valid one. The +tag value is arbitrary, although regular character restrictions for SMTP email addresses apply.

Here is a scenario, Let’s say the users’ email address is User can use plus addresses as unique addresses for services that you sign up for, right after the local part (JohnD) and add (string) of choice. So for instance, to receive all bank statement, the user can end up with something like this:

Plus addressing Limitations

When using plus addressing, there are a few things to keep in mind:

  • Plus addresses aren’t aliases in Exchange Online
    • Hence, it can be used only to receive messages and not send them
    • It does not resolve to a user’s name in Outlook clients, so it is easily identifiable in the To and CC fields
  • In a Hybrid environment, plus addressing won’t work for on-premises mailboxes that do not resolve in Exchange Online
  • Web Developers are aware of plus addresses and some online forms/services won’t accept a plus sign in the email field
  • Some subscription services require the user use the original email address that they subscribed with
    • Can’t unsubscribe with plus email address

Enabling the feature

Enable using the Exchange admin center

  1. Login to the new Exchange admin center (
  2. In the left navigation menu Settings > Mail flow
  3. Select Turn on plus addressing for your organization, and then select Save

Note: After the plus addressing is turned on by default in April 2022, you will see the option Turn off plus addressing for your organization if you are following the above steps. Which will be unchecked meaning it is turned on. So placing a checkmark will turn off plus addressing. See screenshot below.

Enable using Exchange Online PowerShell

Before proceeding further make sure you are connected to Exchange Online,

$o365cred = Get-Credential
Connect-ExchangeOnline -credential $o365cred

The cmdlet uses below syntax:

Set-OrganizationConfig -AllowPlusAddressInRecipients $true

Disable using Exchange Online PowerShell

This setting will be effective only after plus addressing is turned on by default in all organizations starting in late April 2022. Before that happens, plus addressing can be disabled in the O365 tenant by using the AllowPlusAddressInRecipients parameter I described earlier with the value $false value. This can also be proactively set, you don’t have to wait for it to be turned on by default.

To disable plus addressing in the O365 tenant:

Set-OrganizationConfig -DisablePlusAddressInRecipients $true

Determine settings with PowerShell

To determine plus address related settings in the exchange organization:

Get-OrganizationConfig | Select *PlusAddress* | fl

Hope this helped you in understanding the plus address settings in O365.

Thank you for stopping by. ✌

Office 365 – Convert User Mailbox to Shared Mailbox

Scenarios are plenty when O365 admins are requested to convert a user mailbox to a shared mailbox.

Here is one that comes up often,

  • User/Employee leaves the organization and others in the team need access to the user’s mailbox to keep track of the project they were working on

When we convert a user mailbox to a shared mailbox, the mailbox must have a license assigned and after the conversion is complete, we can remove the license.

One little caveat to the licensing part is, without license assigned to the shared mailbox, its size is limited to 50GB. So, before converting, make sure to check the mailbox’s size and to increase the shared mailbox’s size to 100GB, assign a Exchange Online Plan 2 license.

Note: If you are on Exchange hybrid environment, you’ll have to manage your mailboxes using on-premises Exchange management tools.

To convert a user mailbox to Shared mailbox using PowerShell

Before proceeding further make sure you are connected to Exchange Online,

$o365cred = Get-Credential
Connect-ExchangeOnline -credential $o365cred

To convert to shared mailbox:

$Mbx = Read-Host "Enter user's email address for Shared Mailbox conversion"
Set-Mailbox -Identity $Mbx -Type Shared

The -Type parameter also supports the below values:

  • Equipment
  • Regular
  • Room
  • Workspace (cloud-only)

Determine if it worked

To make sure the mailbox has been successfully converted:

$sMbx = Read-Host "Enter email address"
Get-Mailbox -Identity $sMbx | fl DisplayName,RecipientTypeDetails

To convert a user mailbox to Shared mailbox using EAC

Exchange admin center also allows converting a user’s mailbox to shared mailbox.

  1. Login to Exchange admin center, in the left navigation menu, click recipients
  2. Click Mailboxes
  3. Search for the mailbox and select it
  4. In the right side details window, Click Convert under Convert to Shared Mailbox
  5. Click Yes in the warning window
Convert to Shared Mailbox
successfully converted to shared mailbox

Determine if it worked

  1. Login to Exchange admin center, in the left navigation menu, click recipients
  2. Click shared
  3. Search for the mailbox
Shared tab in recipients

Hope this post helped you out.

Thank you for stopping by.✌

Office 365 – Update Primary Email Address in Bulk using PowerShell

In this post, I’ll go over steps on how to update users’ primary email address in bulk.

I had to update the custom domain name address for one of the tenants I manage. When the O365 tenant was setup, I didn’t have my domain name ready for various reasons and the users were setup with @{tenantname} addresses. Once I added the necessary DNS records for O365 and made sure my new domain name is listed as default in the domain tab(Microsoft 365 admin center -> Settings -> Domains) in the list of , I was ready to update the user accounts with the new domain name.

Before proceeding further make sure you are connected to Exchange Online,

$o365cred = Get-Credential
Connect-ExchangeOnline -credential $o365cred

To bulk update accounts from a csv file:

Note: csv file has User,Emailaddress as column headers. Enter the users’ email address with new domain in the csv file. It is strongly recommended to leave the address in the users’ proxy addresses and specifying the new address as PrimarySmtpAddress with SMTP.

$users = Import-Csv C:\tmp\Update-Email\emails.csv
foreach ($user in $users){

$Mailbox= Get-Mailbox -Identity $user.User
$SMTP ="SMTP:"+$user.Emailaddress
Set-Mailbox -Identity $user.User -EmailAddresses $SMTP,$PrimaryEmail -WindowsEmailAddress $user.Emailaddress -MicrosoftOnlineServicesID $user.Emailaddress 


To bulk update all accounts in the O365 tenant:

Note: This below script will change all accounts in the tenant from whatever your enter for the $oldDomain to the $newDomain. So, proceed with caution and comply with your change management process and steps.

$oldDomain = Read-Host "Enter existing domain name in '' format"
$newDomain = Read-Host "Enter new domain name in '' format"

$mailboxes = (Get-Mailbox -ResultSize Unlimited -RecipientTypeDetails UserMailbox).where{$_.PrimarySmtpAddress -like "*$oldDomain"}
foreach ($mbx in $mailboxes){

$PrimaryEmail = $mbx.PrimarySmtpAddress
$newSMTPAddress = $mbx.PrimarySmtpAddress -split '@'
$newSMTPAddress = $newSMTPAddress[0] + $newDomain
$SMTP ="SMTP:"+$newSMTPAddress
Write-Host "Processing: $mbx.Name --> $newSMTPAddress"
Set-Mailbox -Identity $mbx.Identity -EmailAddresses $SMTP,$PrimaryEmail -WindowsEmailAddress $newSMTPAddress -MicrosoftOnlineServicesID $newSMTPAddress

You can also make this change in bulk in the portal as well,

  1. Select all the users whom you wish you update
  2. Click on Change domains
  3. Select the desired domain name from the drop down at the pop-up window
  4. Click Save changes

Thank you for stopping by.✌