Sep 02 2020 02:23 AM
Sep 02 2020 02:23 AM
HI - this my first post & hope someone can help - or reassure :)
I have 10 users with "Microsoft 365 Business Standard" - we all use Windows 10 and office 365 suite (not MS Teams - but would like to).
All users have software installed with the default *.onmicrosoft.com (domain)
Our Email is hosted elsewhere (i understand it can be migrated - but were not ready yet).
Can i add our Domain (lets call it *myFastHostsDomain) and switch all the *.onmicrosoft.com accounts to *myFastHostsDomain.
My worry is Outlook / email / exchange may not work - or get confused.
Will emails start going to another mailbox on the 365 acccount once this is done? And could i use Teams etc with this setup?
Any help would be much welcomed
Sep 02 2020 06:14 AM
Hi, you can certainly add your custom domain into Office 365 without affecting your other email system yes.
As long as you don't change your MX records or Autodiscover records you will be fine. Just add the domain in, verify with a TXT record and you will be able to set your users addresses to yourdomain.com as the primary UPN suffix as opposed to tenantname.onmicrosoft.com.
Just be careful if you are assigning licences to the users that include an Exchange Online licence as this will create a cloud mailbox. This in itself will not affect your existing email routing but if you ever come to the point later down the line where you want to migrate your mail into Exchange Online, then having duplicate mailboxes will cause you extra hassles at that point. You can exclude Exchange Online from the licence assignment to avoid this. This can be done manually, or by group based licencing.
Dec 07 2020 06:42 AM - edited Dec 07 2020 07:07 AM
Hi, we have a similar problem, but we use Microsoft Teams and we need scheduled meetings. This means we need to assign Exchange Online plans for allowing access to calendar, and this gives us some serious problems, since some emails are routed directly to the cloud mailbox instead of honoring what the MX records says.
Is there a way out of this, like forcing Microsoft to always honor MX records when sending email ?
Mar 16 2021 09:00 AM - edited Mar 16 2021 09:16 AM
@GianlucaAmatoDid you find a solution?
We have similar situation -- we have a custom domain linked to Office365 but MX records are set to our custom email provider (we do not use Office 365/Exchange for emails).
However Teams meeting invitations (not just Teams, any invitation from Outlook calendar) are sent to Exchange/Outlook accounts (which are not used) instead of our real email accounts respecting MX records.
Mar 17 2021 01:26 AM
@petrdvorakI made some progress, but I am not satisfied of the results so far.
I tried adding a flow rule in Exchange which forwards all incoming e-mail trough our on-premise SMTP server. This works, but as a side effect, when a meeting is scheduled, the calendar of involved participants is not updated. My guess is that the calendar in Microsoft 365 is updated when an email with the appointment is received, but with the flow rule everything is diverted to our email server.
I would like to try with a flow rule that send everything to our on-premise SMTP server but also keeps the original message in the Exchange mailbox, but I do not know if it is possible.