One account 3 Companies

New Contributor

Hello all.


We are migrating to Office 365 from 2 seperate, hosted exchanges.


The set up is


1 Holding company with 4 employees who work accross all companies and require to be able to send and receive emails from all 3 companies and to participate in "teams" across all companies

1st trade co with employees who need be able send/receive from one email address but need to participate in teams across the group

2nd trade co as per first trade co


is there a way to achieve this without 

a) having to login/logout of the web client

b) creating multiple inboxes using imap? this seems to create a complete copy of the inbox.



Am I missing something obvious or trying to achieve something impossible?


thanks in advance



4 Replies

If those are separate Office 365 tenants and/or external organizations, then the answer is no, not possible - you have to use separate accounts.

Thanks for the response.
I am trying to achieve this by using one tenant with multiple domains and aliases.

If all domains are in the same tenant, you can add as many aliases from as many domains as you want to your users (the limits are in the hundreds). Sending from a different alias is tricker though, as Exchange by default will only allow you to send via the Primary SMTP address. There are certain workarounds for this, such as using a "dummy" Outlook profile, or provisioning the alias to another object (DG, shared mailbox) and granting the user Send As permissions. To ensure email deliver, you then have to also configure some form of forwarding from the DG/shared mailbox to the user's mailbox.

Have a look at ChooseFrom 365 cloud service.