When sending mails as virtual server owner (default account for a virtual server) in username, the sender mail address is wrong !
username is right but the domain is the hostname of the virtualmin server instead of the virtual server domain.
also tried to send mail from roundcube installed via script install. but roundcube refuses to send mail.
this was with outgoing sender mapping disabled, after enabling outgoing sender map we get:
Error
Konnte die Einstellungen nicht ändern : No outgoing address mapping file (sender_canonical_maps) was found in your Postfix configuration!
Call Stack Trace
File Line Function
/usr/share/webmin/virtual-server/save_domain.cgi 95 virtual_server::error
(eval 77) 6 (eval)
/usr/share/webmin/miniserv.pl 2057 (eval)
/usr/share/webmin/miniserv.pl 715 miniserv::handle_request
regards