Open outlook client or switch to contacts it opens login.microsoft or outlook web

[Scherubini]

Hi, after we switched to Modern Authentication with Mfa Active
gradually all users every time they open outlook or switch from outlook to calendar or contacts this web or login window pops uplogin.microsoftonline.com or outlook.office.com
it is solved by enabling webmail but we don't want to solve the problem by leaving webmail disabled
Can you help me
Thank you

[#2]

@Scherubini 

Hello! You've posted your question in the Tech Community Discussion space, which is intended for discussion around the Tech Community website itself, not product questions. I'm guessing based on your question that it belongs to the Security, Compliance and Identity space where I've moved it - please post Security, Compliance and Identity questions here in the future. 

If you feel your content belongs elsewhere on Tech Community, let me know and happy to move it. 

[#3]

this is microsoft's answer
I did some research at my end and thought it was actually a bug.

The Outlook backend team is working on this and we expect the update to roll out next month.

See the official article: 

https://support.microsoft.com/en-gb/office/outlook-unexpectedly-opens-a-browser-window-if-owa-is-dis...