Teams rejection of meeting invitation - WHY?!

Question

Teams rejection of meeting invitation - WHY?!

Danielle Southcott 0

Hello, I am new to Teams. My guests are trying to accept my meeting invitations, however when they click "accept", they are sent a rejection notice. WHY IS THIS HAPPENING?!

Thank you,

Danielle

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3 answers

Your answer

Answer 1

Jayden-P 2,520 Independent Advisor

Hi @Danielle Southcott

I apologize for the inconvenience this issue is causing you and your guests.

I'd like to gather a few more details to understand your situation better.

Could you please confirm the following:

Could you share the exact wording or a screenshot of the rejection notice? Please remove any personal information before posting or sharing screenshots.
Are the affected attendees external guests (outside your organization)? If yes, are they using a work account, personal Microsoft account, or another email provider?
Was the meeting created in Microsoft Teams or Outlook?
Can the affected guests join the meeting if they use the meeting link directly? Or are they unable to access the meeting altogether?

Additionally, if all affected users are external guests, your organization's Teams configuration may be contributing to the issue. Guest access, external access, or meeting policy settings can sometimes prevent external attendees from properly accepting or joining meetings.

Once I have the rejection message and the answers above, I can provide an appropriate direction for your situation.

Meanwhile, you can read these articles to see if it helps in your case:

External users not able to join | Microsoft Community Hub

Unable to invite guests to Teams meetings | Microsoft Community Hub

Danielle Southcott 0 Reputation points

2026-08-12T16:28:25.7433333+00:00
Hello Jayden, thank you!

Could you share the exact wording or a screenshot of the rejection notice? Please remove any personal information before posting or sharing screenshots.
Am waiting to receive a forwarded email or screenshot to provide to you.

Are the affected attendees external guests (outside your organization)? If yes, are they using a work account, personal Microsoft account, or another email provider?
Yes, all affected are external guests.

Was the meeting created in Microsoft Teams or Outlook?
Microsoft Teams

Can the affected guests join the meeting if they use the meeting link directly? Or are they unable to access the meeting altogether?
Unsure
Danielle Southcott 0 Reputation points

2026-08-12T16:30:09.33+00:00

Hello again Jayden, here is an excerpt from the rejection notice:

AM4PEPF00027A67.mail.protection.outlook.com gave this error: Requested action not taken: mailbox unavailable (S2017062302). [AM4PEPF00027A67.eurprd04.prod.outlook.com 2026-08-12T15:13:45.617Z 08DEF7236ED8B544]
Jayden-P 2,520 Reputation points Independent Advisor

2026-08-12T16:39:23.85+00:00
Thank you for the additional information.

The error "Requested action not taken: mailbox unavailable" indicates that the meeting acceptance response could not be delivered to the mailbox associated with the meeting invitation.

Could you please help confirm the following?

Are you able to sign in to Outlook on the web and send/receive emails normally?

Are the affected guests using an Exchange/Microsoft 365 account or a different email provider (such as Gmail, Yahoo, etc.)?
Danielle Southcott 0 Reputation points

2026-08-12T16:46:17.78+00:00

Hello Jayden,

Apparently Teams is using an invented email address: [Moderator note: personal info removed]

[AM4PEPF00027A67.mail.protection.outlook.com] rejected your message to the following email addresses:

[Moderator note: personal info removed] 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.

So I have discovered that I have to completely set up a new email address with Outlook and use Outlook instead of Gmail to use Teams. This is really unbelievable.

Can you please verify? I have a professional email set up with my website etc., business cards and everything. Why should I have to set up a completely new email account in Outlook just to use Teams?

You are really helping me, thank you!! 😭
Jayden-P 2,520 Reputation points Independent Advisor

2026-08-12T16:54:47.3033333+00:00
Please note that this forum is a public platform, and moderators will modify your question to hide your personal information in the description. Kindly ensure that you hide any personal or organizational information the next time you post an error or other details to protect personal data.

Thank you for the clarification.

Could you please confirm:

What email address do you use to sign in to Teams? What subscription do you have on that email address?

Are you using the free/personal version of Teams or Teams through a Microsoft 365 Business subscription?

You also mentioned you have a professional email set up with your website, is it the one you use to sign in Teams? If yes, is it a Microsoft account or another provider account?
Jayden-P 2,520 Reputation points Independent Advisor

2026-08-13T15:48:52.4866667+00:00

Can you please provide the additional information so I can assist you better?
Danielle Southcott 0 Reputation points

2026-08-27T09:00:07.1+00:00
Hello Jayden,

Sorry for not responding sooner. To answer your question:

Are you able to sign in to Outlook on the web and send/receive emails normally?
I use Gmail. I have now established an Outlook account, though I do not understand what email address it is using. My entire company is run using Gmail.

Are the affected guests using an Exchange/Microsoft 365 account or a different email provider (such as Gmail, Yahoo, etc.)? I don't know, they are from all manner of different companies. As far as I understand, all manner of people are receiving the rejection / cancellation notice when they try to accept my invitation.

Therefore, I suppose it must be because I am using Gmail on a Mac. Is it normally possible to use the Teams App if you use Gmail and a Mac?

Answer 2

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Answer 3

Hi @Danielle Southcott

Thanks for your information.

I was able to reproduce a similar scenario in my testing.

In my test, when Microsoft Teams was used with a non-Microsoft email address (Gmail), Teams created a Microsoft identity in the background and meeting responses were routed to a Microsoft-generated Outlook address. That explains the Outlook.com account with random user name behavior.

When attendees accepted the invitation, the acceptance response was sent to that Outlook address rather than directly to the Gmail mailbox.

In my testing, the attendees were still able to join the meeting successfully by using the Teams meeting link directly. The issue only affected the meeting acceptance response. Based on my testing, this behavior appears to be related to using a non-Microsoft email address with Teams rather than the use of a Mac device.

Therefore, my current understanding is that the rejection message is occurring because the meeting response is being routed to a Microsoft-generated Outlook address associated with the Teams account, while the primary account itself is a Gmail account. As a result, the acceptance email cannot be processed correctly, even though the Teams meeting remains accessible through the meeting link.

In summary, this does not appear to be a macOS issue. The behavior seems to be related to the account being configured with a non-Microsoft email address rather than a Microsoft 365 or Exchange Online mailbox. I'd recommend you to give the direct Teams meeting link. Or if your prefer scheduling meeting via email, setting up a Microsoft account is an alternative approach. (personal or business account depends on your need)

I hope this explains your concern.