Teams meeting invitations use an internal alias instead of my primary email - responses bounce

This behavior matches a Microsoft account that uses a third-party or non-Outlook address as the sign-in alias. In that case, Teams and related meeting response flows can use a generated outlook_[long series of letters and numbers]@outlook.com address or another alias instead of the expected primary address, and acceptance/decline responses can fail or bounce.

The supported self-service action is:

1. Open Edit account info: https://account.live.com/names/manage
2. Select Add email.
3. Create a new Outlook.com alias.
4. Set that new Outlook.com alias as the primary alias.
5. Keep the existing domain address as a secondary alias if sign-in with that address is still needed.
6. Sign out of Teams and Outlook, then sign back in.

Important supported facts:

• Aliases on a Microsoft account share the same password, contacts, storage, subscriptions, and account settings.
• The primary alias is the one that appears on devices and is the address Microsoft account experiences commonly use.
• Personal Microsoft accounts and Microsoft 365 work or school accounts cannot be merged.
• If the account is showing the "Which account do you want to use?" prompt because both a personal account and a work or school account use the same email address, changing the personal account’s primary alias can remove that conflict.

What cannot be done from the documented self-service options:

• There is no documented way here to directly edit or remove the generated internal Teams/Outlook response address if it is tied to how the Microsoft account is configured.
• Support agents are not allowed to access and change account details directly.

If the Outlook.com alias workaround has already been tried and the problem still persists, the remaining documented path is to use Microsoft Support through the account support flow.

References:

• Change the email address for your Microsoft account | Microsoft Support
• Outlook.com email account appears as "outlook_[long series of letters and numbers]@outlook.com" in Outlook for Windows | Microsoft Support
• Which account do you want to use? | Microsoft Support
• Outlook.com calendar acceptance replies fail for external domains (550 5.5.0 S2017062302) - Microsoft Q&A
• Teams appointment response issue - Microsoft Q&A
• When I create a meeting and send an invite, the acceptance returned to be is undeliverable - Microsoft Q&A When a recipient gets my invite to a MS Teams meeting acceptances are not being delivered - seems to not recognise this email address
• Wrong email in Teams - Microsoft Q&A When I send and invitation through Team for a meeting, the email that shows is not the one registered. It's with "numbers,letters,******@outlook.com"