How to send emails from a secondary user

How to send emails from a secondary user

Hello, I registered to Zoho with myname@mydomain.com and I can send emails with this email address from Zoho's website. Then I added a new account: support@mydomain.com, the problem is that I cannot access the emails for this user. I lost an hour navigating trough the interface without understanding how to access with support@mydomain.com. It seems impossible!