452 4.3.1 Temporary System Error

452 4.3.1 Temporary System Error

I'm trying to send emails to the SUPERUSER PRIMARY user  leticia@leticiakacessorios.com.br and it isn't working. I can't send emails with this account. When I try to configure it in the Mailadmin, it gives me ACCESS ERRORs.

All I get is " 452 4.3.1  Temporary  System Error" and it keeps retrying for days until it gives up.

The other account,  alexei@leticiakacessorios.com.br works fine.