Forum Discussion
Office 365 multi tenant architecture and deployment
The problem here is that you cannot have the same domain added in more than one O365 tenant. What you can do is use different domains or add subdomains, and use say blabla.tenant-a.com in tenant-b.com's organization.
Other than that, you can forward the messages based on the default tenant.onmicrosoft.com domain (for the receive part) and "spoof" the domain for the sending part. Which is far from ideal and will likely cause you troubles.
For the SPO part B2B/external users should work, as Juan mentioned.
I don't need to add the same domain to both tenants. Only sending and recieving mails over the same domain is my goal. At tenant A i can work maybe with a exchange sending connector. But what a bout tenant B? He need to redirect incomming mails for users in tenant A to Tenant A?
Is maybe a better solution when i install one AD Server in Azure and connect both clients to them?
You need it as accepted domain in order to receive messages. As I mentioned there are several workarounds (use the default domain, use subdomain, use forwarding), but it depends on the details.
Not sure what a server in Azure will help you with the task at hand. Is the question perhaps about only a few people needing such functionality, so that you can for example configure both tenant-a and tenant-b profile in the same Outlook client?
Not really, because tenant A don't have their own external mailadress. Only using the mailbox in tenant A but sening and recieving mails should go over tenant b.
My Idear was to place a Ad Server in Azure with AD Synch and connect both tenants to them.
Sending messages from Tenant B to Tenant A is easy. I create a contact in tenant b with a riderect to the onmicrosoft address of tenant a. You need to set the smtp alias from tenant b as default in this contect after creating. Now when i send a mail to user1@tenant-b.com it will be redirectet to user1@tenant-a.com. In the mail the recieptentadress is user1@tenant-b.com. So incoming is working good. Know i need tell tenant-a that they can send in the name of tent-b.com. But i can't add an accepted domian to the exchange of tenant-a.
How can i configure the exchnage on tenant a to connect to tenant b for sending mails in the name of tenant b?