Invitation Issue in Teams: 'Requested Action Not Taken: Mailbox Unavailable' Error

Question

Hi everyone,

I'm encountering an issue when inviting people to a Teams meeting. They receive the invitation, but when they try to respond, they get the following error message: 'Requested action not taken: mailbox unavailable'. As a result, I don't receive any confirmation of their attendance, and in my Teams calendar, a question mark remains next to their names under the guest list.

Has anyone else experienced this issue? I'd appreciate any guidance on how to resolve this.

Thanks in advance for your help!

Answer 1

Hi @Floor Meijer

According to your case description, you encountered an error that the mailbox is unavailable when inviting others to join the meeting. Please try the following possible solutions:

• Check the status of the recipient's mailbox: Make sure the recipient's mailbox is valid and there is no setting to block or filter Teams meeting invitations.
• Resend the invitation: Resending the meeting invitation can solve unexpected problems. You can try to delete the original invitation and then resend it.
• Use the web version of Teams: Try to use the web version of Teams to create and send meeting invitations to see if the problem can be solved. https://teams.microsoft.com/v2/
• Teams add-in problem: If you invite through Outlook, please check whether the Teams meeting add-in is enabled.

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