Hi all,

is it at all possible for a cross forreste to share same SMTP domain (accepted domain)?

EX DomainB have @DomainA.com as additional smtp address and vice versa?

T

Hi ,

yes it is possible and it is called as the shared SMTP namespace between the exchange forests.So on such case you need to have "@DomainA.com" in both the exchange forest's accepted domain list as "internal relay " 

Please reply me if you have any queries.

Hi Nithyanandham and thanks for your prompt reply.

So means this can work between Exchange ON prem and Exchange online as well?

Currently DomainA is in hybrid deployment (using DirSync) and DomainB is a pure Exchange Online tenant.

DomainA is in Europe and DomainB is in USA.

How should MX and autodiscover record point?To domain A ?

(autodiscover and MX is pointed to ON prem exchange, then redirected to Exchange online for DomainA).

What about OAB and calendar sharing?

Thanks!

Hi,

According to your requirement, I suggest you can refer to the below article to configure SMTP Namespace Sharing between two Exchange Forests:

https://ibrahimnore.wordpress.com/2012/09/02/cross-forest-smtp-namespace-sharing-part-1/

Please note: Since the website is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information. And the changes made in the above blog is not supported officially by Microsoft.

Regards,

David  

• Marked as answer by Off2work 21 hours 22 minutes ago

Hi ,

Thanks for your reply.

We can point autodiscover and MX record as per our wish , whether it can be to the firewall in on prem or else to exchange online.

I mean to say that both the options will work .

Thanks all for all your help,case closed! :D