Invitees get a delivery error when accepting a teams invite

Dear @Shane Twomey,

Good day! Welcome to Microsoft Q&A forum!

Based on your description, I understand that when you create a Microsoft Teams meeting, invitees encounter a delivery error after accepting the invitation. Specifically, the meeting response is being sent from an auto-generated Outlook address, which results in a non-delivery/bounce-back message, as shown in the screenshot. You’re looking to understand why the acceptance response is coming from this address and how to configure Teams so that meeting responses are sent from your own email address instead.

I sincerely apologize for the inconvenience caused by this issue.

Regarding this situation, meeting responses can be sent from an auto-generated Outlook.com alias rather than your actual email address, which can result in non-delivery or bounce-back errors.

This typically occurs when:

• A non‑Outlook email address (such as a third-party or custom domain address) is registered as the primary alias on a Microsoft account, or
• There are multiple aliases on the account and the primary one is not an Outlook.com or Hotmail.com address.

When this happens, Outlook may send replies (including Teams meeting acceptances) using the system-generated Outlook.com address, which is not able to receive replies, leading to the “address not found” error you’re seeing.

These are the workarounds for this situation:

Option 1: Set up the account manually in Outlook (IMAP or POP)

This approach ensures Outlook sends messages using your actual email address rather than the system-generated alias.

• Close Outlook.
• Press Windows key + R, type outlook /profiles, and select OK.
• In the Choose Profile window, select Options > New.
• Create a new profile name and select OK.
• Select Advanced options, then choose Let me set up my account manually.
• Enter your email account details and complete the setup using the settings provided by your email provider.
• Set the new profile as the default and reopen Outlook.

This configuration helps ensure that meeting responses and emails are sent from your correct address.

Option 2: Change the primary alias to an Outlook.com address

If your Microsoft account has multiple aliases, setting an Outlook.com or Hotmail.com address as the primary alias can prevent the issue.

• Sign in to your Microsoft account and manage your aliases.
• Set an Outlook.com or Hotmail.com address as the primary alias.
• Remove and re-add the account in Outlook for Windows so the change is fully applied.

After this, Outlook and Teams will use a valid, reply-capable address when sending meeting responses.

Once the account is set up using one of the methods above, meeting acceptances should send successfully from your proper email address.

For reference: Outlook.com email account appears as "outlook_[long series of letters and numbers]@outlook.com" in Outlook for Windows

I hope this information is helpful. Please follow these steps and let me know if it works for you. If not, we can work together to resolve this.

Please understand that our initial response does not always resolve the issue immediately. However, with your help and more detailed information, we can work together to find a solution.

Any updates you’re able to share would be really helpful. I appreciate your time and look forward to hearing how things are going! 

Thank you for your time and patience.

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