sendmail should throw an exception but does not

[Clodoaldo]

I need to know if an email was refused for whatever reason, it makes
no difference.

The email is sent to an email address that does not exist in a foreign
domain. I can see in the postfix log that the email was sent and
bounced with the error code 550.

The problem is that sendmail should throw an exception but it does
not. And the returned dictionary is empty as if the email was
accepted.

d = smtpserver.sendmail(sender, recipient, m.as_string())

I guess that the error code returned by the destination mail server is
not is not forwarded to the client by my mail server.

Regards, Clodoaldo Pinto Neto