[exim] need fully-qualified hostname

After an update senfing to certain domains i get this DFN:

504 5.5.2 <w>: Helo command rejected: need fully-qualified hostname

I have checked in the /var/lib/exim/config.autogenerated file and found
this:


##############################################
# the following macro definitions were created
# dynamically by /usr/sbin/update-exim4.conf
.ifndef MAIN_PACKAGE_VERSION
MAIN_PACKAGE_VERSION=4.89-2+deb9u6
.endif
.ifndef MAIN_LOCAL_DOMAINS
MAIN_LOCAL_DOMAINS=@:localhost:w.trail.it:trail.it
.endif
.ifndef MAIN_RELAY_TO_DOMAINS
MAIN_RELAY_TO_DOMAINS=empty
.endif
.ifndef ETC_MAILNAME
ETC_MAILNAME=w.trail.it
.endif
.ifndef LOCAL_DELIVERY
LOCAL_DELIVERY=mail_spool
.endif
.ifndef MAIN_RELAY_NETS
MAIN_RELAY_NETS=: 127.0.0.1 : ::::1
.endif
.ifndef DCreadhost
DCreadhost=empty
.endif
.ifndef DCsmarthost
DCsmarthost=empty
.endif
.ifndef DC_eximconfig_configtype
DC_eximconfig_configtype=internet
.endif
.ifndef DCconfig_internet
DCconfig_internet=1
.endif
##############################################


domainlist local_domains = MAIN_LOCAL_DOMAINS

domainlist relay_to_domains = MAIN_RELAY_TO_DOMAINS

hostlist relay_from_hosts = MAIN_RELAY_NETS

daemon_smtp_ports = 25 : 465 : 587
tls_on_connect_ports = 465
SYSTEM_ALIASES_FILE_TRANSPORT = address_file

.ifndef MAIN_PRIMARY_HOSTNAME_AS_QUALIFY_DOMAIN
.ifndef MAIN_QUALIFY_DOMAIN
qualify_domain = ETC_MAILNAME
.else
qualify_domain = MAIN_QUALIFY_DOMAIN
.endif
.endif

(…)
#################################################

but exim on helo say just 'w' not the FQDN .
Where is the problem ?

--
Leonardo Boselli