Exchange Online: How to enable your tenant for modern authentication

The Office 365 tenant/resource host (Exchange Online, SharePoint Online and Skype for Business Online) will need to be configured to accept a modern authentication connection. Here is the per service state of modern authentication by default :

• Exchange Online - ON by default.
• SharePoint Online - ON by default.
• Skype for Business Online - ON by default.

Steps

This article explains how to enable your Exchange Online tenant to support modern authentication.

1. Connect to Exchange Online using remote PowerShell: refer here ventej.blogspot.com
2. Run the following command:
• Set-OrganizationConfig -OAuth2ClientProfileEnabled:$true
3. Verify that the change was successful by running the following:    
• Get-OrganizationConfig | ft name, *OAuth*

Ref: Microsoft article