User can sign into OWA with login@domain.com but gets no mail box exception when signing in with user logon.

Joseph 1 Reputation point
2020-08-05T13:17:40.947+00:00

Hey guys,

I've came across a problem where I have a user who is able to sign into OWA no problem with his full email address name@keyman .com. When signing in with his AD credentials he successfully gets signed in but is redirected to the "A mailbox couldn't be found for" error. Any advice would be appreciated as I have had this issue sitting in the back for a while and have not been able to find a cause or a resolution.

Thanks in advance,
Joey

Outlook Management
Outlook Management
Outlook: A family of Microsoft email and calendar products.Management: The act or process of organizing, handling, directing or controlling something.
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Microsoft Entra ID
Microsoft Entra ID
A Microsoft Entra identity service that provides identity management and access control capabilities. Replaces Azure Active Directory.
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5 answers

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  1. Andy David - MVP 144.2K Reputation points MVP
    2020-08-05T16:45:33.277+00:00

    Ok, I suspect the alias/SamAccountName on that account has been changed so its not working logging on as that.
    Can you check that in AD or Exchange and confirm it matches what the user is using?
    Note that logging on as the UPN (User@keyman .com) is just as valid and if that works, I'd continue to use that.

    If this is only affecting one user, I would start there.

    1 person found this answer helpful.
  2. Joseph 1 Reputation point
    2020-08-05T13:20:25.983+00:00

    I forgot to add, this is the only user in the organization that I know of facing this issue.

    0 comments
  3. Andy David - MVP 144.2K Reputation points MVP
    2020-08-05T13:32:03.903+00:00

    Hi
    I think we need more information here.

    Is this on-prem or Exchange Online?

    Does Outlook and/or Mobile Devices Work?

    What link is being used to access OWA?

    Did this ever work, when did it start if so?

    is the mailbox set as User Mailbox?

    get-mailbox <user> |FL type

    Is it enabled for OWA?

    get-casmailbox <user>

    Can you post the complete and exact error message?

    Does it fail with all browsers?

  4. Andy David - MVP 144.2K Reputation points MVP
    2020-08-06T19:18:08.203+00:00

    Can you check the application event logs on the server they are accessing when they try to logon and it fails? Wonder if anything is generated there.

    Can you confirm that the mailbox alias and AD SamAccountName match?

    0 comments
  5. Eric Yin-MSFT 4,386 Reputation points
    2020-08-11T09:39:48.257+00:00

    I am writing here to confirm with you how the thing going now?
    Have you checked the UPN and SamAccountName?

    0 comments