Having trouble setting this up.

john.doe@domain1.com is working fine

john.doe@domain2.com fails, "user in other organization" or "email address already in use".

Nothing is used for domain2, it is another domain of mine that was hosted elsewhere.  

For domain2.com I've updated the MX and other records to zoho.  The records pass validation.  

If I set domain2 as a domain alias of domian1 then email sent to john.doe@domian2.com is received in domain1 but I need the ability to send from john.doe@domain2.com so I can't use domain aliases.  

I have a 2 user license.  Can I not have the same name used on two different domains?

I have a 3rd domain let's call domain3.com.  I also had that hosted externally using john.doe@domain3.com.  

Do I have to buy another license to be able to use john.doe@domain3.com?   

So basically I need 1 user license per domain.  Is that right?  I'm the only user.  There is no one else.  

Am I better not to buy multiple licenses for one account, but pretend I am 3 or 4 different people and assign one domain per account with one user license per account?  i.e. - set up multiple accounts as if I am not the same person.  

account 1 = john.doe@domain1.com, 1 user license

account 2 - john.doe@domain2.com, 1 user license

account 3 = john.doe@domain3.com, 1 user license

etc.

Thanks.