Additional domain DNS setting while using CloudFlare DNS

[mmike]

I am using CloudFlare DNS for mydomain1 dot com, hosted on VPS 1
The Mail-in-a-Box is setup on box.mydomain1 dot com, and hosted on VPS 2

I have two questions:

1. Additional Domains’ DNS setup
   To setup a second domain (mydomain2 dot com) to use Mail-in-a-box. What DNS shall I be setup in domain registrar?

Shall I modify my domain registrar’s default DNS, and change them to
ns1.box.mydomain1 dot com
ns2.box.mydomain1 dot com

Or, I shall just add a MX record in the domain registrar’s DNS control panel?

2. Sending out emails from mydomain2 dot com:

How to configure in order to let sender view the emails are from mydomain2.com?
Or they will see the emails are sent out from mydomain1 dot com?

3**. All email arrive in inbox**

How to make all emails arrive in Inbox?
A few emails went to spam folder.
I tried to setup rule in the inbox, as below, but it seems not working: I still see some messages being sent to spam.

[alento]

@mmike

What DNS shall I be setup in domain registrar?

Why not use Cloudflare as well???

@mmike

How to configure in order to let sender view the emails are from mydomain2.com?

Not sure that I understand … you will use an email account for a user on domain2 … so it will be from domain2. To add a second domain to MiaB simply add an email account or alias to MiaB and then copy the necessary DNS records to your DNS provider.