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Since using the Teams app on my MacBook, some contacts are now having their emails rejected. Previously their emails were received.

Karen D 0 Reputation points
2025-10-23T09:29:19.28+00:00

Since using the Teams app on my MacBook, some contacts are now having their emails rejected. Previously I received their emails without issue.

Background: I have used Teams via the web as a call participant but now need to organise Teams calls and invite people to them. I have subscribed annually to a Microsoft Family product since 2018. I ran the Microsoft Teams app on 18 Oct on my MacBook Air. I set up and invited someone to a meeting but on sending their acceptance to the Teams email invitation they received a bounce back message. The reply email is not in my email account when I use it natively with BT via a browser, nor in my Mail, and isn't in Spam/Junk.

I subsequently amended the Teams calendar invite to a different time and they were again unsuccessful in sending the acceptance reply getting the following message:

AMS1EPF00000040.mail.protection.outlook.com rejected your message to the following email address [my name followed by numbers and then @outlook.com (don't want to publicly post my details although this may be anonymised?)]

A communication failure occurred during the delivery of this message. Please try to resend the message later. If the problem continues, contact your email admin.

AMS1EPF00000040.mail.protection.outlook.com gave this error:

Requested action not taken: mailbox unavailable (S2017062302).

*[AMS1EPF00000040.eurprd04.prod.outlook.com 2025-10-23T07:09:11.842Z 08DE110C2F038B00]
*
Another contact who I had been successfully emailing with over the past couple of years also had a bounce back email from me yesterday for the first time. I had joined a Teams call with him the previous day (which he had set up) and joined via the Teams app instead of using the web browser version which I would have formerly done. Not sure if this is therefore related or relevant?? He received the following bounce back email when he tried to send a general email to me .

‘btinternet.com suspects your message is spam and rejected it.’

Note he was not responding to a Teams generated invitation, he was replying to a general email which had been in progress for a couple of weeks.

Microsoft Teams | Microsoft Teams Free | Settings | Other
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  1. EmilyS726 172.5K Reputation points Independent Advisor
    2025-10-23T12:20:55.54+00:00

    Hello,

    It sounds like you are using a third party email address, such as Gmail or Yahoo, as the sign-in username/alias for your Microsoft account. Is that correct?

    When your Microsoft account uses a non-Microsoft email address, it does not have its own email functionality. The actual sending and receiving of emails still happens through your third party email provider. As a result, when you send a meeting invitation through Teams, Microsoft cannot access your external email to send it. Instead, it sends the invitation using a randomly assigned Microsoft email address, one that ends in outlook.com. This is why recipients cannot reply to the invite directly. However, your meeting itself is not affected.

    To give your Microsoft account proper email functionality, you can create a Microsoft-based email alias and set it as the primary alias. Here is how:

    Go to https://account.live.com and sign in to your personal account.

    Click on "Your Info," then choose "Sign-in preferences," and select "Add an alias."

    Choose to create a new alias. It will allow you to create one that's outlook.com.

    After creating it, set it as your primary alias.

    Keep your current third party email as a secondary alias. Do not remove it.

    You can then check emails at https://www.outlook.com. If you prefer, you can also enable email forwarding in the settings so that all messages go to your usual email address and you do not have to check multiple inboxes.

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