cd /opt/zimbra/conf wget https://raw.githubusercontent.com/stevejenkins/hardwarefreak.com-fqrdns.pcre/master/zmprov mcf zimbra Mta Restriction 'check_reverse_client_hostname_access pcre:/opt/zimbra/conf/fqrdns.pcre' Postscreen is a pre-screening process at the MTA level that can be used to reject spammers by doing additive scoring from a variety of sites. Full configuration details will be added to this wiki prior to release.Our current recommended Spam Assassin customizations comprise three complementary methods: We found that increasing the log level from 1 to 2 puts in /var/log/the specific Spam Assassin tests which each email has triggered.zmprov/zmlocalconfig are both permissible and the recommended way to perform Postfix customizations for supported keys. Mark Stone, Reliable Networks Our client base is very nervous about spam-delivered malware but even more concerned about "false-positives" i.e. Consequently, we've had to develop tweaks to improve Zimbra's default Spam Assassin configurations.The results have been that users with very public email addresses who typically receive several hundred to more than a thousand emails per day will see no more than ~3 spam emails per day in their Inbox.Compiling the SA rules helps decrease the amount of time it takes to score email. In ZCS 7 and ZCS 8, customizing Postfix is a mix of zmlocalconfig and zmprov settings.
If your end-user base is more tolerant of false positives, then you can tighten things up.
This generally rejects larges amounts of bot traffic where the bots are sending out email directly rather than an authenticated user going through the ISP outgoing SMTP servers.
Support for using this PCRE method is built into ZCS 8.7 and later.
The problem is that many of the RBL services embedded in Spam Assassin and configurable within Zimbra limit the number/rate of queries they accept from a particular DNS server.
Since almost all RBL queries will never be cached, the queries get done by the forwarders.(As we understand it, Zimbra may start shipping a DNS server bundled with Zimbra in a later release.) One configuration nuance to DNS is the use of forwarders in your BIND9 configuration.