Created: 1/16/23

Updated: 1/17/23

This is a guide to block legacy authentication with Exchange Online.

1. 1. 1. Open up PowerShell
      2. Follow this guide to get connected to Exchange Online

Type this to check for other Authentication Policies:

Get-AuthenticationPolicy | Format-Table -Auto Name

1. 1. 1. Note: if you never set up an Authentication Policy, none would appear, this is normal.

Create a new Authentication Policy via:

New-AuthenticationPolicy -Name “BlockBasics

To verify that all basic settings are disabled type this:

Get-AuthenticationPolicy -Identity “BlockBasics”

1. 1. 1. Note: by default, all are disabled when the policy is created

To enforce this for a single user type:

Set-User -Identity someone@domain.suffix -AuthenticationPolicy BlockBasics

To enforce this for a group of users type:

Get-Mailbox -Resultsize Unlimited | Set-User -AuthenticationPolicy BlockBasics

1. 1. 1. Note: Press “A” to confirm

To enforce for a group of users but exclude a user or group type:

Get-Mailbox -Resultsize Unlimited | ? {$_.displayname -notlike “John Doe*”} | Set-User -AuthenticationPolicy BlockBasics

1. 1. 1. Note: Press “A” to confirm
      2. This will exclude users that are called “John Doe”

Something handy, to check out your AuthenticationPolicy type:

Get-AuthenticationPolicy -Identity “BlockBasics”

Note: useful Exchange 2019 Powershell commands list

Whelp this is a wrap, cheers!

-Trevor