I have a domain pointing it's MX records at Outlook.com at this time and I would like to add new users to my Zoho account.

I looked at the dual-delivery option, but I am unable to set it up properly.

I add in the 'Destination to route the emails' field the MX name of the outlook server and set 'Change SMTP envelope to match the provided destination' to On.

With this setup I receive all the emails in my Zoho inbox although the user is only set in Outlook. 

Also, if I set it to 'Email Delivery Options' to dual delivery or email routing I receive the email in Zoho but I also receive a bounced email back in the email from which I sent the test. The issue reported is a '550: mailbox unavailable' error and the email address contains the user name and the MX record name instead of the domain name.

Any help is appreciated.

Thanks,

Denis