What namespace are you using for SMTP? You can use an existing one or add: https://learn.microsoft.com/en-us/exchange/certificate-requirements Edge servers are not required. so really could just use owa.contoso.com as the SMTP namespace as well and then set that on the send connector to from on-prem to Exchange Online
Exchange certificate URL's
Susan Dodds
211
Reputation points
Exchange 2019. SAN certificate from 3rd party CA. Confirmation on required URL's. URL's: owa.contoso.com autodiscover.contoso.com Any other specific requirements for the SAN that is required for exchange online hybrid with my exchange 2019 server?