I own 2 different domains, that I have validated in Zoho. I have no problem using any of my 2 domains when sending mails between the same owned domain addresses and between owned domain with any external domain. Example:

Consider I own domains <company_name>.com and <company_name>.net.

Sending mail from test.sender@<company_name>.com to test.reciever@<company_name>.com works fine, as well as sending mail between test.sender@<company_name>.com to any.reciever@<gmail or any other>.com and does work the other way around as well.

But trying to send email from  test.sender@<company_name>.com to  test.reciever@<company_name>.net, the mail appears to be sent with no error, mail appears in the "Sent" folder with the "delivered check status" but mail never arrives on the test.reciever@<company_name>.net inboox.