Amavisd-new policy banks and sasl_username in the returning smtpd instance

[Damian]

> Could perhaps be, that Amavis is not storing the XCLIENT variable 
> LOGIN (http://www.postfix.org/XCLIENT_README.html 
> <http://www.postfix.org/XCLIENT_README.html>) in mail_via_smtp() where 
> should handle LOGIN XCLIENT attribute?.
>
Postfix can speak XFORWARD towards Amavis, and Amavis is able to 
interpret it. According to [1] there is no sasl-related attribute.

> I'm sending mail traffic to Amavis, using XCLIENT extension
I was not aware that Postfix smtp can speak XCLIENT, I only knew about 
smtpd via smtpd_authorized_xclient_hosts. How do you do that exactly? 
Also, I do not see any XCLIENT-related Amavis code.

[1] http://www.postfix.org/XFORWARD_README.html