Multiple email accounts in MacOS mail app

Multiple email accounts in MacOS mail app

Hey, 
I am facing a problem while using Zoho mail app on macos.
The clear description of the problem:
  1. I am managing multiple Zoho accounts and each of them have some custom email addresses.
  2. address1@domain1.com is my main account, address2@domain2.com
     is my second account, keep in mind that, they are both associated with different zoho accounts. each of them are superadmins in 2 different accounts. 
  3. When I am logging in the 1st address, it works. then 
  4. from settings in macos app, I navigate to the Mail Accounts
    tab and I try to add new email from zoho (provider) then I fill the details but it gives me internal error. I can not login to multiple accounts in one mail app

please help me