Teams Meeting Responses go to the wrong address

Hi,
I am organizing a conference at Microsoft Teams. For this, I invite participants outside of my organization as guests and schedule meetings. Some participants complained that they cannot accept the meeting invitations. When they press "Accept" in outlook calendar, they get an error: "Your message was not delivered to <Teamname>@groups.<organization_domain> could not be found."
What can I change in Team's settings to solve this issue?
Thanks