multi domain within office 365

New Contributor



Don't know exactly how should we cope with domains that we have. We've got three different domains within organization:


  • - main company domain for communication with customers, suppliers, etc. 
  • - product domain, for SaaS solution maintained by us - currently all users in 365 are attached to that domain, as we have been evaluating that service that way. e-mails from were migrated already
  • - legacy local domain - not used anymore, however, older customers may still send e-mails to that domains

Now, we'd like to implement the following scenario:


  • - all users within an organization should have ability to receive and send e-mails from this domain
  • - mail sent to should be redirected to Sending from not possible
  • - functional mailboxes - sales, support, and couple of personal mailboxes - messages received should be redirected to group of users, ability to send e-mails from domain

Domains are registered within office365 and MX and TX records are set, but I do not know how should we proceed. Questions:


  • Is it possible to have redirection from to without the need to create (and acquire and apply additional license) to each user within organization?
  • How should I switch main domain - from to - can I somehow change domain for existing users?
  • I understand, that for domain, I should create separate users and apply 365 licenses (cheapest e-mail only license)?

Please advise, all comments appreciated. 





9 Replies

You can simply add additional email aliases to those users. As in, user John  has primary SMTP address and additional aliases and You can have dozens of those added, with no additional cost, and any message addressed to any of those will be delivered in the same mailbox. Sending is only possible by the Primary SMTP address by default, so you got that issue sorted too.

OK, so if I want to receive e-mails from different domains, I just create aliases - I checked it and it works. 


Additional licenses are needed only if I want to send e-mails from different domains - so each SMTP requires one license?


To change primary address, I will have to create alias for that one, and then set it as a primary address. The question - what about my mailbox - will remain intact if I switch domains?



Yes, a licensed mailbox can only send from one primary SMTP address at a time (without any address rewriting at the transport, etc...).  So I believe you would need another licensed mailbox to simultaneously send from another domain (another primary SMTP address). You could keep switching the primary address though.


Yes, create an alias with a different domain and set it as the primary.  The mailbox will remain intact. It will have an effect on sign-in and any scheduled Skype meetings, etc.. as indicated by the warning when you switch the primary:


Switch Primary Email Address.png



There are different workarounds you can use in order to send as additional aliases, including some third-party tools that make the process painless. One of the common method is to create a shared mailbox with said address and grant yourself Send As permissions. You can configure some form of forwarding if you want to keep the messages coming to one and the same mailbox. But in general the method can be challenging to use for some users.

Hi Krzystof,


You can also create a shared mailbox if you need to send as from other email address.

Yes, that could be done.  Note the shared mailbox will require a separate license though (unless he can meet all of this needs for this mailbox, with the one shared mailbox).


Alternatively you can use ChooseFrom365 cloud service to send as alias.

@Victor Ivanidze forgetting the security implications of running mail through a 3rd party, your prices don't even compete with just buying an additional license from MS and setting up as a mailbox in it's own right.

@Bootloop ,




MS Office 365 Business Essentials costs $60 per user per year

IvaSoft ChooseFrom 365 one alias annual fee is $25 per user per year


How did you compare?