Yes, that's a scenarios best addressed by Conditional Access policies, more specifically the "location" condition: https://learn.microsoft.com/en-us/azure/active-directory/conditional-access/location-condition
Outside of CA policies, you can also use the per-user MFA settings, where you can too define "trusted locations". However, this method has limited customizability compared to CA, and Microsoft will eventually deprecate the per-user MFA controls, so best use CA.
How to enable MFA for Outlook client using outside corporate network

hi,
i am looking for adding the MFA for Outlook Client (outlook 2019) using a conditional access when user access outside corporate network. is it possible via a conditional access policy or any other.
any ideas will be helpful.
Thanks
Pavan.
3 answers
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Vasil Michev 67,366 Reputation points MVP
2022-01-25T20:08:05.503+00:00 Joyce Shen - MSFT 16,371 Reputation points Microsoft Vendor2022-01-26T05:25:31.413+00:00 Hi @pavan kumar
According to my search, I found this link discusses the similar issue like yours, please check if this is your scenario: MFA not working in Outlook 2019 – Exchange Online
Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.Users can access Outlook on the web without any problems and get notifications sent to the “Microsoft Authenticator” app to approve or SMS if they choose one of the other authentication options.
When it comes to Outlook 2019 they just repeatedly get asked for their email credentials in a standard type popup box as opposed to the newer MFA style popup that you see like when you login to https://office.com where it asks for email, then password, then MFA option.And the solution provided:
1.Run PowerShell as admin
2.Connect to Exchange Online
3.make sure -OAuth2ClientProfileEnabled is set to $true, if not, running the command belowSet-OrganizationConfig -OAuth2ClientProfileEnabled $true
This pretty much enables the use of MFA now for your Exchange Online tenant. It can take a few hours for things to propagate and for Outlook 2019 to make use of this. If you need to speed this process up you can add the following registry key to the users computer. Make sure to close Outlook first.
HKEY_CURRENT_USER\Software\Microsoft\Exchange
On the Edit menu, point to New, and then click DWORD Value.
Type AlwaysUseMSOAuthForAutoDiscover, and then press Enter.
Right-click AlwaysUseMSOAuthForAutoDiscover, and then click Modify.
In the Value data box, type 1, and then click OK.
Exit Registry Editor.Some related official document links:
Connect to Exchange Online PowerShell
Enable or disable modern authentication for Outlook in Exchange Online
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pavan kumar 371 Reputation points2022-01-26T13:03:53.427+00:00 Thank you for the info
We are in hybrid and all mailboxes in o365. Is there any additional steps that I need to take care for enabling a modern authentication.
we are exchange online all mailboxes.