Outlook login

The displayed OwaUserHasNoMailboxAndNoLicenseAssignedException usually means Outlook on the web cannot find an Exchange mailbox for the signed-in identity, so a Microsoft 365 administrator must verify the mailbox and Exchange Online license if this is a work or school account.

Work or school account

First, sign out of other Microsoft accounts and open Outlook in an InPrivate or Incognito window using the intended work or school address. This rules out a cached session for another identity.

Then ask your Microsoft 365 administrator to:

1. Open Microsoft 365 admin center → Users → Active users.
2. Select your account and open Licenses and Apps.
3. Verify that:
   • An Exchange-capable Microsoft 365 license is assigned.
   • The Exchange Online service within that license is enabled.
4. Assign the appropriate license or enable Exchange Online, and then select Save changes. License assignment requires at least the License Administrator or User Administrator role.^1^
5. Allow provisioning to finish, then sign out and test Outlook again. Provisioning normally takes less than 30 minutes but can take up to 24 hours.^2^

If Exchange Online is already enabled: Microsoft Q&A guidance for this exact exception recommends that an administrator clear Exchange Online, save, re-enable it, and wait for synchronization before testing again.^3^

Temporarily removing Exchange Online disconnects a regular user mailbox, so this should be done only by the administrator after checking any hybrid, retention, or compliance requirements. Mailbox data is ordinarily retained for 30 days after license removal, but administrators should not use this toggle casually.^1^

If the license was removed or expired, reassign it promptly. For a regular mailbox without a hold, Exchange Online disconnects the mailbox immediately and permanently deletes it after 30 days if the license is not restored.^4^

If the problem remains after 24 hours:

• Run the mailbox-provisioning diagnostic from the Microsoft 365 admin center, if available in your cloud environment.
• Check Health → Service health for an Exchange Online incident.
• Open Support → New service request so Microsoft can inspect mailbox provisioning.

If this is a shared mailbox

Do not sign directly into an unlicensed shared-mailbox account. Sign into Outlook on the web using your own licensed mailbox, then open the shared mailbox from that session. Direct access using an identity with no mailbox or license can produce this exception.^5^

Personal Outlook.com or Hotmail account

Microsoft 365 business licensing steps do not apply to personal addresses such as @outlook.com or @hotmail.com.

• If you cannot sign into the Microsoft account at all, use Microsoft’s Microsoft account sign-in helper. Outlook.com support cannot reset or recover the account through the mailbox support channel.^6^
• If the Microsoft account signs in but Outlook still shows this mailbox exception, contact Outlook.com support because the personal mailbox may require service-side provisioning assistance. If Outlook opens elsewhere, select Help, search for the issue, and under Still need help? select Yes.^6^

Do not post the full diagnostic details publicly; session IDs, request IDs, tenant information, and email addresses should be removed from screenshots.

References

1. Assign or unassign licenses for users in the Microsoft 365 admin center
2. Delays in provisioning of user/mailbox or synchronizing changes in Exchange Online
3. I cannot open outlook email - Microsoft Q&A
4. Can't access the mailbox of an unlicensed user in Exchange Online
5. UserHasNoMailboxAndNoLicenseAssignedError - Microsoft Q&A
6. How to get support for Outlook.com | Microsoft Support