> If my email host refuses to send the email (476 connections denied), we
> still get the message that the email has been sent - and no error message.
> 
> How do I or can I send authentication information to the email server?

This is not implemented right now, since the SMTP server at our institute does
not use authentication, so I could not test it. If you give me access to a
SMTP server with authentication, I could implement it.