Service unavailable; Client host [xx.xx.xx.xx] blocked using zen.spamhaus.org – fase positive
The “list” zen.spamhaus.org combines all spamhaus.org’s filters including the PBL
PBL is a DNSBL database of end-user IP address ranges and this could give false positivs
Instead you could use: sbl-xbl.spamhaus.org
Rumors says, When Zen is used solely as the single test to block spam it could lead to false positives.
Configuration:
/etc/postfix/main.cf
Change:
smtpd_client_restrictions = permit_sasl_authenticated, reject_rbl_client zen.spamhaus.org
to:
smtpd_client_restrictions = permit_sasl_authenticated, reject_rbl_client sbl-xbl.spamhaus.org
Alternatives:
xbl.spamhaus.org
sbl-xbl.spamhaus.org
zen.spamhaus.org
bl.spamcop.net
/etc/Mailscanner/spam.lists.conf
Restart postfix and Mailscanner