Unable to sign in

For a newly created Microsoft work email account that cannot sign in to Outlook on the web, the most likely causes are account, mailbox, or sign-in protection issues. Use these checks and actions:

1. Confirm the account and mailbox are actually enabled

• Even if the Microsoft Entra ID (Azure AD) user account exists and can authenticate, the Exchange Online mailbox may be disabled or terminated.
• This typically results in Outlook on the web failing to load the mailbox even though sign-in appears to work at the identity layer.
• Ask the organization’s Microsoft 365/tenant administrator to:
  • Check the mailbox status in Exchange Online (for example, verify that AccountDisabled is not set to True).
  • If the mailbox is disabled, re-enable the mailbox for the user.
  • Optionally, check for other disabled mailboxes if multiple new users are affected.
• After the mailbox is re-enabled, try signing in again to Outlook on the web.

2. Rule out temporary sign-in protection blocks (MFA / repeated attempts)

• If multiple failed attempts were made while trying to sign in to the new account, Microsoft Entra multifactor authentication may temporarily block additional attempts as a security measure.
• If this is the case:
  • Wait before trying again, or
  • Use a different MFA method if one is configured.
• If there is any suspicion that someone else might be trying to access the account, contact the IT administrator so they can review Microsoft Entra sign-in logs and adjust MFA settings if needed.

3. If still unable to sign in

• Contact the organization’s Help desk or Microsoft 365 administrator and provide:
  • The exact error message shown when trying to sign in.
  • Confirmation that this is a newly created work account.
  • Confirmation whether other users in the tenant can sign in successfully.
• The admin can then:
  • Verify the user is licensed correctly for Exchange Online/Outlook on the web.
  • Confirm the mailbox is provisioned and not disabled.
  • Review Entra sign-in logs and conditional access/MFA policies for blocks.

References:

• Not able to have access to my email ! - Microsoft Q&A
• Common problems with two-step verification for a work or school account