This account is not supported in Outlook for Windows due to the license provided by your work or school

I had the same issue like many others. I have switched back to the old version of Mail on my Windows and it works again, allowing multiple accounts (company and gmail accounts).

Will switch back to the new outlook only when this problem will be fixed by MICROSOFT.. no one is upgrading licenses for just having visibility on already purchased for accounts!! If by they time I will be "forced" to switch to the new outlook, the problem will still be there, I will "bye bye" outlook and move to google business. Up to you MS..

I am having the exact same issue. We use a number of emails with a basic licence that don't require the use of apps. Think emails like @contact or @info.

We are a non-profit and cannot afford to upgrade licenses for emails that multiple people share.

This Outlook upgrade is a complete downgrade and I'm not happy about this.

Yep, in same but... saw the 'Try New Outlook' toggle and was excited to see the preview... that didn't last long. I quickly noticed all my Exchange plans FROM MICROSOFT don't work! It was so bizarre I couldn't believe or comprehend this decision. I'm a web developer and have referred countless clients to use $4/month exchange plans, which are great and have seriously made me an ambassador for them... but if you can't even use this with their flagship product Outlook, what is the point? I switched back to the old Outlook and not going to upgrade my license, especially since I already pay for a 365 subscription AND exchange... mind boggling.

To help keep us on track, let me summarize what we know so far:

This is not something that is "broken," and the indications are that this is not something Microsoft is going to "fix". It appears that all of us who are waiting for a fix might be waiting for a long time.

This is because Microsoft has made the conscious decision to prevent less-expensive Microsoft 365 licenses from using New Outlook for Windows. If you have an A1/E1/F1/Business Basic/EXO P1/EXO P2 or similar "low-cost' Microsoft 365 license, you will not be able to use it with New Outlook for Windows. Microsoft has officially confirmed that they've made this choice, and they have not provided any explanation as to why.

There are some anecdotal suggestions that this has been fixed already. As of January 5th, it is not fixed. The problem still exists. There are some anecdotal suggestions that some people have made it work. These can be grouped into three categories:

1. People who switched to New Outlook before Microsoft issued the restrictive update seem to be okay for now.
2. People who have copied one or more settings database files or registry entries from a working computer to a new computer can sometimes make it work for a previously-working specific account.
3. People who purchase a more expensive license, then add their account to New Outlook, then downgrade that license, have in some cases reported success.

The reasons for these exceptions seem to be that - at the moment - New Outlook only checks the license when the account is first added to New Outlook. However, all of these workarounds seem unreliable (not everyone can make them work) and none of them are supported. Moreover, if Microsoft continues to pursue this destructive course, it's only a matter of time before they modify New Outlook to do a periodic license check, which will invalidate all of these workarounds and disconnect all of these users. But in ALL of these cases, if you remove the account from New Outlook, you will not be able to re-add it, and if you try to migrate to New Outlook from any other program with any of these licenses, they will not work, and if you buy new licenses for the inexpensive accounts, they will also not work. So these workarounds are not solutions in any real way, they're just some people finding a loophole for a specific case.

There are those who suggest that this is in line with Microsoft licensing. We respectfully disagree. We've reviewed their own licenses and terms, and believe that Microsoft is currently violating their own terms of use. But regardless of that, the reality here is that this course is destructive for Microsoft: They support FREE accounts from all the major providers including themselves, which makes the whole thing ridiculous on its face.

It is unfathomable to us why Microsoft is doing this, but we hope to get this reversed. But the only way we can get it reversed is if enough people complain. But it's critical to realize that Microsoft does not participate in this forum, and they are not seeing this thread. The only way to complain about this is to do it in the place where Microsoft actually pays attention, which is in their feedback portal.

To that end, we have created a master feedback item here: https://feedbackportal.microsoft.com/feedback/idea/2f7925cb-3a80-ee11-a81c-000d3ae46fcb . If you are upset about this issue - and you should be! - the best thing to do is to go to that link, and comment and upvote it. They read that feedback, and act on the highest upvote count and highest comment count items. That is the only way to get Microsoft's attention.

And don't stop there. Get your co-workers, get your company administrators, get everyone you know who is a Microsoft 365 customer to go to that same item and upvote it. If we could get many employees from just a few impacted companies to upvote and comment, we could get this on Microsoft's radar much more quickly. The issue is gaining more traction and attention as more people trip over this, but the more votes we can get, the faster the outcome will be.

All of the details of the issue are documented there so, please, if you're reading this, take a moment now to go upvote and comment so that we can get this insanity reversed as quickly as possible.

Thanks,

Glen

If it is a shared mailbox make sure the user has full access delegate permissions via Admin Portal or Exchange and right click the primary account in New Outlook and click add Shared Mailbox. Relaunch and they should be under the Shared with you folder.

If the account is unique:

Make sure the user has full access delegate permissions via Admin Portal or Exchange. Log into the account through portal.office.com (the one that you are getting the error trying to add), launch the web version of Outlook, and then try adding account via the Add Account button on New Outlook. If it doesn't work, probably need to upgrade the license?