Outlook Login Error

Question

Outlook Login Error

Rachel 0

Can no longer access Outlook. When trying to access Outlook via app, receive the following error:

We couldn't reach the email server. Please try again.

Can log in to Microsoft account on a browser, but receive the following error when trying to access Outlook:

Checked the status of the user's account via admin's user management, account shows active.

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Answer 1

Hi @Rachel,

Thank you for reaching out and sharing the details of the errors you’re seeing in Outlook. I know how disruptive it can be when you’re unable to access email - especially when both the Outlook app and Outlook on the web return different errors.

Your OWA error trace includes err: AccountTerminationException, along with Error 440 and esrc: StartupData, which typically indicates that the mailbox object itself is disabled, even when the Entra ID (Azure AD) user account still appears active. In these situations, the user can sign in normally at the identity layer, but Exchange Online treats the mailbox as terminated or disabled, preventing Outlook and OWA from loading.

This also aligns with the Outlook app message, “We couldn’t reach the email server. Please try again,” since the client can’t establish a mailbox session when the mailbox is in a disabled state.

Below are the actions required on the admin side. Kindly share these instructions with your IT administrator so they can complete the necessary checks:

1/ Check whether the mailbox is disabled

Get-Mailbox ******@domain.com | fl AccountDisabled

If the result shows AccountDisabled : True, that matches the behavior indicated by the AccountTerminationException error.

2/ Re-enable the mailbox

Set-Mailbox ******@domain.com -AccountDisabled $false

3/ (Optional) Identify any other disabled mailboxes

Get-Mailbox -ResultSize Unlimited | Where-Object { $_.AccountDisabled -eq $true }

After re-enabling, have the user try signing into Outlook on the web again.

Here are the next steps you can try after your IT administrator completes the checks above:

A/ Refresh authentication

Sign out of all Microsoft sessions
Sign back in using https://outlook.office.com/

User's image

B/ Clear browser session

Try InPrivate/Incognito
Or clear cookies for outlook.office.com

C/ For the Outlook app error (“We couldn’t reach the email server”)

If the mailbox is re-enabled but the desktop client still fails:

Remove cached credentials (Windows Credential Manager > Windows Credentials > Generic Credentials > remove Outlook/Office entries)
Disconnect and re-add the Work/School account under Windows Settings
Restart the device and sign in again

These steps address cached authentication failures that can persist after mailbox reactivation.

I hope this information helps. Please try the steps and let me know whether they resolve the issue. If the problem persists, we can work together to find a solution.

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Kristen-L 12,020 Reputation points Microsoft External Staff Moderator

2026-03-13T15:18:56.79+00:00

Hi @Rachel,

I hope you’re doing well.

Just checking in on the support thread to see if my previous response helped resolve your issue. If you’re still having trouble or have any questions, feel free to reach out - I’m happy to assist anytime. Thanks again for your collaboration, and I look forward to hearing from you soon.

Warm regards.

Answer 2

The error message includes AccountTerminationException with status code 440, which indicates that the mailbox/account for Outlook on the web has been terminated or blocked on the service side, even though the Azure AD/Microsoft 365 user object still appears as Active in admin user management.

Because this is a server-side mailbox state, client troubleshooting (reinstalling apps, clearing cache, changing devices, or browsers) will not resolve it. The account must be checked and remediated by an administrator with the appropriate rights in the tenant.

Recommended actions for the admin:

Verify mailbox status
- In the Microsoft 365 admin tools, confirm that the user not only exists and is Active, but also has an Exchange Online license assigned.
- If the license was removed and re-added recently, allow time for provisioning and then test Outlook on the web again.
Check for access restrictions or termination
- Review any security, compliance, or lifecycle policies that might have soft-deleted, blocked, or terminated the mailbox (for example, account termination workflows, litigation/hold changes, or automated deprovisioning).
- If the mailbox has been soft-deleted or is in a terminated state, restore or re-enable it according to the organization’s procedures.
Confirm sign-in works outside Outlook
- Since sign-in to the Microsoft account portal works, focus on Exchange/Outlook service specifically rather than identity sign-in.
If Outlook mobile is also blocked
- If Outlook for Android or iOS shows an access denied or cannot reach server error and the account is governed by mobile access policies, the account may be blocked for Outlook mobile as well. In that case, the IT admin must review and adjust any conditional access or mobile application management policies that deny Outlook mobile access.
Escalate within the organization
- If the admin cannot see any obvious reason (license, mailbox state, or policy) for the AccountTerminationException, the issue must be escalated to the organization’s higher-level Microsoft 365/Exchange Online administrators or support channels so they can check the backend mailbox state and remove any termination/block flags.

End users cannot fix AccountTerminationException themselves; only the IT admin or Microsoft support (via the admin) can restore access.

References:

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Outlook Login Error

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