Microsoft Account Errors

Fix Outlook Displays Alias as outlook_ with Random Characters

WPS Content Manager Sep 28, 2026 869 views

Question details

Users need to resolve an issue where their Outlook.com alias displays incorrectly as a long string of random characters, causing email delivery and reply failures.

How to Fix Outlook Displaying an Alias with Random Characters (outlook_...)

Product: Outlook for Windows
Device & OS: Windows
Scenario: Sending and receiving emails in the Outlook desktop application using an Outlook.com alias.
Observed behavior: The sender's email address appears as "outlook_" followed by a long series of letters and numbers (e.g., outlook_123456789ABCDEF@outlook.com) instead of the actual email address, leading to undeliverable replies and missing messages.

Before you start

Ensure you have your Microsoft account credentials ready, as you will need to sign in to the Microsoft account management website in your browser to update your primary alias settings.

Solution 1Recommended

Change Your Primary Alias to an Outlook.com Address

This issue typically occurs if a third-party email address (like an ISP email or Gmail) is set as your primary account alias. Changing it to a native Microsoft domain resolves the display error in Outlook for Windows.

Outlook for Windows uses Microsoft Exchange to connect to Outlook.com accounts. If your primary alias is a non-Microsoft email address, the server cannot parse it correctly and generates a temporary 'outlook_[random-string]@outlook.com' address.

Sign in to Microsoft Account

Open a web browser and go to the Microsoft account website. Sign in using your current credentials.

Navigate to Account Info

Click on 'Your info' at the top of the page, then select 'Edit account info' in the Account info section.

Change the Primary Alias

Under the 'Account aliases' list, locate an email address ending in @outlook.com or @hotmail.com. Click 'Make primary' next to that address.

Re-add the Account in Outlook

Open Outlook for Windows, go to File > Account Settings > Manage Profiles. Remove the problematic account, then click 'Add' to set it up again using the new primary @outlook.com alias.

Change Your Primary Alias to an Outlook.com Address

Account Synchronization: After changing your primary alias online, it may take a few hours for the changes to fully sync across Microsoft's servers before you re-add the account in Outlook for Windows.

Solution 2

Create a New Outlook.com Alias (If Needed)

Use this solution if your Microsoft account only contains third-party email addresses and you do not currently have an @outlook.com alias to set as primary.

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Frequently Asked Questions

Why does my Outlook alias show as a long random string of characters?

This happens when your Microsoft account's primary alias is a third-party email address (such as a Gmail, Yahoo, or an ISP address). The Exchange server Outlook uses cannot properly process the non-Microsoft domain as the primary identifier, so it auto-generates a temporary 'outlook_[string]' address instead.

Will changing my primary alias delete my other emails or accounts?

No. Changing your primary alias only updates the main email address associated with your Microsoft account for sign-in and display purposes. It does not delete any associated emails, contacts, or your existing secondary aliases.

Do I need to remove and re-add my account in Outlook after changing the alias?

Yes, it is highly recommended to remove the account from Outlook for Windows and add it back after changing the primary alias. This ensures the local Outlook client establishes a fresh connection with the Exchange server using the correct display name and routing addresses.

Can I still sign in with my old email address after changing the primary alias?

Yes, as long as you do not delete the old email address from your list of aliases, you can continue to use it to sign in to your Microsoft account and other Microsoft services.

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