ZCS Administrator Guide 8.0

Open Source Edition

Anti-Spam Training Filters

The automated spam training filter is enabled by default and two feedback system mailboxes are created to receive mail notification.

Spam Training User for mail that was not marked as spam but should be.

Non-spam (referred to as ham) training user for mail that was marked as spam but should not have been.

The mailbox quota and attachment indexing is disabled for these training accounts. Disabling quotas prevents bouncing messages when the mailbox is full.

How well the anti-spam filter works depends on recognizing what is considered spam. The SpamAssassin filter learns from messages that users specifically mark as spam by sending them to their junk folder or not spam by removing them from their junk folder. A copy of these marked messages is sent to the appropriate spam training mailbox.

When ZCS is installed, the spam/ham cleanup filter is configured on only the first MTA. The ZCS spam training tool, zmtrainsa, is configured to automatically retrieve these messages and train the spam filter. The zmtrainsa script is enabled through a crontab job to feed mail to the SpamAssassin application, allowing SpamAssassin to ‘learn’ what signs are likely to mean spam or ham. The zmtrainsa script empties these mailboxes each day.

Note:

New installs of ZCS limit spam/ham training to the first MTA installed. If you uninstall or move this MTA, you will need to enable spam/ham training on another MTA, as one host should have this enabled to run zmtrainsa --cleanup. To set this on a new MTA server zmlocalconfig -e zmtrainsa_cleanup_host=TRUE

Disabling the Spam Training Mailboxes

The ZCS default is that all users can give feedback when they add or remove items from their junk folder. If you do not want users to train the spam filter you can disable this function.

1.	Modify the global configuration attributes, ZimbraSpamIsSpamAccount and ZimbraSpamIsNotSpamAccount

2.	Remove the account addresses from the attributes.

zmprov mcf ZimbraSpamIsSpamAccount ‘’

zmprov mcf ZimbraSpamIsNotSpamAccount ‘’

When these attributes are modified, messages marked as spam or not spam are not copied to the spam training mailboxes.