This domain need to be the one that belongs on your organization, that may be, this domain should be the 1 you've registered with Microsoft 365. For more information, see Insert a domain to Microsoft 365. Certificate-dependent connector configuration: Make sure that your on-premises email server is configured to https://vmware-migration55555.amoblog.com/how-much-you-need-to-expect-you-ll-pay-for-a-good-zimbra-support-premium-48428007