Blocking spams for hosted zimbra

[ozlecz]

hello

ZIMBRA email server is hosted and spams just keep coming.

How can we block spams. Could we use pfblockerng? or what is best for this?

Many thanks

[BBcan177]

Zimbra uses Postfix, so your first step is to use DNSRBLs. Your biggest bang would be to add Spamhaus Zen.

You can run the following command to see what restrictions have been configured:

zmprov gacf | grep zimbraMtaRestriction

Recommend the following settings:

zimbraMtaRestriction: reject_invalid_hostname
zimbraMtaRestriction: reject_non_fqdn_hostname
zimbraMtaRestriction: reject_non_fqdn_sender
zimbraMtaRestriction: reject_unknown_client
zimbraMtaRestriction: reject_unknown_hostname
zimbraMtaRestriction: reject_unknown_sender_domain
zimbraMtaRestriction: reject_rbl_client zen.spamhaus.org
zimbraMtaRestriction: reject_rbl_client bl.spamcop.net
zimbraMtaRestriction: reject_rbl_client b.barracudacentral.org
zimbraMtaRestriction: reject_rhsbl_client dbl.spamhaus.org
zimbraMtaRestriction: reject_rhsbl_reverse_client dbl.spamhaus.org
zimbraMtaRestriction: reject_rhsbl_sender dbl.spamhaus.org

For pfBlockerNG, I wrote a script to import over 50 Blocklists here:
https://forum.pfsense.org/index.php?topic=86212.msg549973#msg549973

It has a MAIL section which will also help reduce SPAM.