The answer to this question is:
acl_check_rcpt:
... your stuff here, then abit later towards the end of the ACL
accept
authenticated = *
# JolieRouge This took some time to search out
# 2006-09-27 <pille@struction.de>
# force empty domain, when fixing header during submission, as we use fqdn in our usernames (to avoid doubled domains)
# 2007-01-30 <pille@struction.de>
# added /sender_retain option to take any given address from 'Sender:'-header (used as 'Return-path:' and for 'MAIL FROM:'-SMTP-command)
control = submission/sender_retain/domain=
The bottom line control = submission/sender_retain/domain=
is used when your logins are a full email address.