[Exim] 3.35 : virtual domains -> Mailer-Daemon@virtualdomain

I intend to host a number of mail domains, each user at each domain having
his own maildir

I put together the following directors, consulting example c009

Whenever I send a message to fubar@???, example.com being a handled
virtual domain and fubar a non existent user I get a Mailer-Daemon error, as
I expected. I checked book/faqs for ways whether I can have the
Mailer-Daemon address originate from @example.com instead of the machine's
host name, but haven't yet managed :-(

I'm sure it's possible, unless it's a NO-NO practice

# ---virtual user directors---
vmail_aliases:
driver = aliasfile
domains = lsearch;/etc/vmail/vmail.domains
search_type = lsearch
file = /etc/vmail/$domain.aliases

vmail_localuser:
driver = aliasfile
domains = lsearch;/etc/vmail/vmail.domains
file = /etc/vmail/$domain.users
search_type = lsearch
transport = vmail_maildir_delivery
no_more
# ---virtual user directors---

thanks everyone
B.