Can't connect Outlook 2016 to my O365 Mailbox

[Andrew Connell]

Scenario:

• I have an Office 365 account with the email foo@contoso.com
• I have an old MSA account with the email foo@contoso.com
• Windows 10 - Creators Update (but tried this with a fully patched version immediately before updating to Creators Update
• Outlook 2016 latest (installed from Office 365

In the past, I had no problem with this.

I login to Windows 10 with my MSA account. Within Windows 10 => Settings => Accounts, I see my MSA account listed as "Outlook" and can firm it's using a Hotmail server to sync.

When I try to add another account in Windows 10 for Exchange using the same email, it tells me that email is already in use.

When I try to add my Office 365 account to Outlook, it constantly rejects the credentials I enter. Instead, it re-prompts me to enter the credentials... except it autofills my email as "MicrosoftAccount\foo@contoso.com".

No matter if I use my Office 365 (Azure AD) password with what's provided or if I remove "MicrosoftAccount\" from the email address, Outlook refuses to connect to it.

The behavior is that because I'm using the same email, Outlook now assumes it's an MSA account and refuses to use the domain with the autodiscovery DNS entry for my domain to resolve to O365 Exchange servers to lookup the account.

The result: I can't use Outlook 2016 for my Office 365 email.

This was not the case in the past. I rebuilt the same machine in September 2016 and had no problem with this same setup. So something changed in Windows 10 / Outlook 2016 to impact this. 

[#2]

Thanks for appreciation:)

[#3]

I'm hoping after two years that OP has resolved his issue, but for anybody else that continues to have issues connecting an Office 365 account to Outlook and none of those tools and methods linked in this article helped you, then hopefully you'll benefit from the fruits of my pain. 

With 2FA enabled I could not add an account in Outlook, with 2FA disabled I could. When 2FA was turned back on I was thrown into a perpetual loop where it kept asking for my password.  The password was correct, but according to this article 2FA is not compatible with Office apps and you need an "App Password": https://www.microsoft.com/en-us/microsoft-365/blog/2014/02/10/multi-factor-authentication-for-office...

I don't find this to be a consistent thing since numerous others have no problem adding an O365 account with 2FA enabled to Outlook, however, it was the solution that worked for me.  It was a little difficult to get working since Outlook wouldn't even give me the option to enter a password (the magic App Password), but once I was given the option to input a password I fed it the App Password and it works now.  

Best of luck!

[#4]

I'm hoping after two years that OP has resolved his issue, but for anybody else that continues to have issues connecting an Office 365 account to Outlook and none of those tools and methods linked in this article helped you, then hopefully you'll benefit from the fruits of my pain. 

With 2FA enabled I could not add an account in Outlook, with 2FA disabled I could. When 2FA was turned back on I was thrown into a perpetual loop where it kept asking for my password.  The password was correct, but according to this article 2FA is not compatible with Office apps and you need an "App Password": https://www.microsoft.com/en-us/microsoft-365/blog/2014/02/10/multi-factor-authentication-for-office...

I don't find this to be a consistent thing since numerous others have no problem adding an O365 account with 2FA enabled to Outlook, however, it was the solution that worked for me.  It was a little difficult to get working since Outlook wouldn't even give me the option to enter a password (the magic App Password), but once I was given the option to input a password I fed it the App Password and it works now.  

Best of luck!

[#5]

@Andrew Connell 

I had to go into my User I disabled the MFA as well as disabling security  defaults in the Azure Active Directory. Issue resolved by following the steps below from admin.microsoft.com:

• Go to Users > Active Users > {AFFECTED USER} > Manage multifactor authentication > {AFFECTED USER} > Disable
• Go to Azure Active Directory > Azure Active Directory > Properties > Manage Security Defaults > Set Enable Security Defaults > No

Hope this helps!

Habib