Domain Prefix before Email address when connecting Office 365 email to Outlook app

Oliver Lennox 106 Reputation points
2021-02-05T12:56:28.623+00:00

Hi there,

We have a client who was using Azure AD sync to connect their O365 tenancy to a local domain controller. The DC has long since gone and they have been cloud only for several years now. The Set-MsolDirSyncEnabled flag has been disabled in O365 Azure to say it's no longer linked.

On the whole, everything is working fine except when users sign into Outlook for the first time where they are prompted to login with the username "OLDDOMAIN\email@mathieu.company .com". This is confusing for the users and is breaking the policy which should be silently signing users into Outlook automatically.

Does anyone know how to fix this? I thought it would be something going on in Azure AD but now I'm wondering if it might be an Exchange Online issue?

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2 answers

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  1. Ashok M 6,506 Reputation points
    2021-02-08T09:15:16.423+00:00

    Hi @Oliver Lennox ,

    Usually for Office365, it will be with the email address to be entered at the credential prompt. If the prompt occurs with olddomain\email@mathieu.company .com then can you check the below,

    1. Is that device still joined to old domain
    2. Any cached credentials in credential manager with olddomain reference
    3. How the users are logging in to the device (domain\username or emailaddress)?

    Does it happen only while creating a new outlook profile?
    Also, any recent changes as you have mentioned that it was working fine for several years?

    Ideally, if the AD is removed, device should have work or school Microsoft account in the local accounts and login will be with email@mathieu.company .com.

    If the above suggestion helps, please click on "Accept Answer" and upvote it

    0 comments No comments

  2. Oliver Lennox 106 Reputation points
    2021-02-08T09:29:24.747+00:00

    Hi Ashok,

    1. No, this is happening on brand new devices that are Azure AD joined
    2. No, this is happening when logging in for the first time on a new device.it is affecting multiple users though I'm not 100% if everyone
    3. The users login with the email/O365 account e.g. olly@Work .com
    4. Yes it's what Outlook defaults to when you create a new email profile. The main issue is that Outlook is unable to auto-login with the linked Windows 10 work/school account and
      silent login is failing. You have to manually delete the domain prefix and enter the password, at which point it logs in and sets up the Outlook account perfectly fine.
    5. We've had this problem since the domain was unlinked from O365, for several years. It's always been a minor annoyance but we're now trying to do more with Intune and device
      auto-provisioning and it's becoming a real pain. I believe all the steps were followed for unlinking the domain from O365 but maybe something was missed?

    Thanks