Office 365 share maildomain

Occasional Contributor

Hi guys,


i know that it isn't possible to verifiy one external domin to more than one tenant. But i have the problem, that my customer need to use his own tenant (legal thinks), but need to communicate with the mailaddress from the other tenant. Mail redirection from one tenant to the other one is no problem. But to sending mails in the domainname of the other tenant is not possible. Do you see a possibility maybe with an hybrid szenario or do you know a special kind of software that can support me?




2 Replies

Maybe you could look into Azure B2B i do not know if it works.

Within Office365 it is not possible

you can achieve this by routing all email traffic through your on-premises infrastructure. There you can place a mailgateway which performs email address rewrite.

If you do this, you must also ensure that replies to these addresses will be delivered correctly, so this gateway must receive the mails and rewrite them for incoming mails to the O365 smtp addresses of the users to ensure they are routed to the right persons. I am sure there are many gateway solutions which are able to do that, I personally prefer the iQ.Suite because it has other features, too, e.g. Antivirus, Antispam, encryption, ...


This above is a highly complex scenario.. Isn't it an option to create this person a mailbox in the other tenant? Tha's much easier and you don't have these routing issues.