Teams Group Mail onpremise Exchange

[MarcBaeuml]

hi all,

actually we receive a 550 5.1.10 RESOLVER.ADR.RecipientNotFound error if we mail to a created e-mail group in teams. it's a hybrid environment and AD Connect and Exchange Hybrid Configuration is running. Out and inbound Connectors are available in Exchange 2019 and M365.

but if a user creates a teams group and assing a mail adress group@domain.com it is only visible and reachable at online mailboxes. the on premise exchange did not find the mailadress, because the adress is only visible online. the area of the m365 connector is domain.mail.onmicrosoft.com so i think the group adress has to be group@domain.mail.onmicrosoft.com

or is this a sync problem of AD Connect oder Exchange Hybrid? how we can sync back created teams groups on m365? i tried group writeback in AD Connect without an improvement.

have someone a similar environment?

Thank you for any help you can offer

Marc

[#2]

@MarcBaeuml the group writeback is necessary to show up in the GAL for your on-premises users and requires Azure AD Premium P1 licenses. I can recommend to use a subdomain that will be created in your on-premises organization, because the MX record of that specific domain has to be configured to use EOP and no on-prem or third-party gateway. For more information, please see the Microsoft docs article: https://docs.microsoft.com/en-us/exchange/hybrid-deployment/set-up-microsoft-365-groups