Hello everyone, we have a CRM 2016 on premise we are testing the configuration of mailboxes and we are having some problems to get the correct configuration. I detail a little more.

The mailboxes are all configured in Microsoft 365. Considering that basic authentication will be disabled in Exchange Online, we set up one of the accounts with the modern MFA authentication from the M365 dashboard.

But when we perform the mailbox approval from CRM we get the following error:

>Exception : Unhandled Exception: Microsoft.Exchange.WebServices.Data.ServiceRequestException: The request failed. Error en el servidor remoto: (401) No autorizado. en Microsoft.Exchange.WebServices.Data.ServiceRequestBase.EndGetEwsHttpWebResponse(IEwsHttpWebRequest request, IAsyncResult asyncResult) en Microsoft.Exchange.WebServices.Data.SimpleServiceRequestBase.EndInternalExecute(IAsyncResult asyncResult) en Microsoft.Exchange.WebServices.Data.MultiResponseServiceRequest`1.EndExecute(IAsyncResult asyncResult) en Microsoft.Exchange.WebServices.Data.ExchangeService.EndSyncFolderHierarchy(IAsyncResult asyncResult) en Microsoft.Crm.Asynchronous.EmailConnector.MonitoredExchangeService.EndSyncFolderHierarchy(IAsyncResult asyncResult) en Microsoft.Crm.Asynchronous.EmailConnector.ExchangeSyncSteps.ExchangeSyncAsyncRemoteStep`2.AfterCall() en Microsoft.Crm.Asynchronous.EmailConnector.ExchangeSyncSteps.ExchangeSyncAsyncRemoteStep`2.Execute() en Microsoft.Crm.Asynchronous.EmailConnect...

your credentials are correct, we validate the login from the browser to the webmail client. you have user in CRM, security role assigned, receive and send mail without problems, also you have an Exchange Online license assigned.

Are we missing any additional configuration? either in CRM, Exchage or M365 Panel.

Any suggestion would be welcome, thank you very much.

P.S.: sorry for my poor English. hehehe.