Would an internal relay domain work without Active Directory trust
Hi, I manage an Exchange environment and we are merging with a new company. The requirement is for a new domain to be setup and hosted by ourselves. All users will have this domain but a handful of users will have their mailboxes hosted on the other organizations mail server with a different primary domain. For these users we will be forwarding their email over to the other server. They will then need to be able to reply as our domain name (we will work on all required DNS records to get this part working). Question is the best way to forward those emails across to the other mail server and meet all 3rd party email DNS checks etc. Testing forwarding from our external mail gateway and also Exchange server. When adding an accepted domain I can make it an internal relay as not all recipients exist in my org. Would this scenario work without an Active Directory trust between the two orgs? Would the send connector for that domain happily route over the internet to the other orgs mail server or does it need to be private. Thanks
