Something

The message could not be sent because one of the recipients was rejected by the server. 
The rejected e-mail address was 'wainux@gmail.com'. Subject 'Prubea de envio de correo local', 
Account: 'mail.agsa.com.py', Server: 'mail.agsa.com.py', Protocol: SMTP, Server Response: '553 
sorry, that domain isn't in my list of allowed rcpthosts (#5.7.1)', Port: 25, Secure(SSL): 
No, Server Error: 553, Error Number: 0x800CCC79