Office 365 mixed mode setup

[Lisa Hammond-Marsden]

Hi, I am setting up a customer on O365. He has a business with no domain, and uses an NTLworld email account. He also works for a second business and has an email address with their domain. They have no plans to move to O365. How should I set up these email addresses within O365 and without touching the MX record of the second company domain? Thanks in advance

[#2 · Accepted solution]

You cannot. If the second company does not want to move to O365 then you cannot register their domain. The first email address is an ISP and not owned by the company, so you cannot. In the case of the first you could register an name like the company name in O365, for example 'firstcompany', but this would give your client firstcompany.onmicrosoft.com as their email address domain. That's a bad idea. Best idea, buy a domain for the client and use that and not virginmedia.com and forward the emails from the ISP to Exchange Online

[#3]

Thanks for the reply Brian. This is as I'd thought, but I was hoping I was wrong.