Spam Filtering

Tigerwave uses SpamAssassin for spam filtering and SIEVE for automatic mail filtering and sorting.  SpamAssassin assigns each email message a score which indicates the likelihood of that message being spam.  The higher the score, the more likely the message is spam.  SpamAssassin adapts to the type of email you receive and becomes more adept at identifying spam over time.

Spam filtering determines spam scores and what spam score threshold must be met before the message is tagged as likely spam; the default threshold is greater than or equal to 5.0.   By changing the subject line, SpamAssassin helps you to identify messages that are likely to be spam.

Message filtering settings determine what spam score is needed before a message is moved out of your Inbox and into the "Spam/AutoFiltered" folder; the default threshold is greater than or equal to 10.0.

When a message is received by the server, it is first processed by SpamAssassin, which based on the spam filtering settings marks it with a spam score, and if the score is high enough (greater than or equal to 5.0 by default), tags it by inserting "[SPAMpoints=<score>]" at the front of the message's subject.

Next, the message is examined by the SIEVE mail filtering/sorting system, and in the default configuration at Tigerwave Networks, if the score is high enough (greater than or equal to 10.0 by default), the message is redirected into the "Spam/AutoFiltered" folder instead of into the Inbox.

Messages that are marked as spam that are not really spam should be moved by the user into the Spam/ToBeLearnedNonSpam folder.  Within 24 hours, the messages will be learned by SpamAssassin as being non-spam, and they will be moved to the Spam/LearnedNonSpam folder, where they will stay forever unless the user moves them to a different folder or deletes them.

You should  move messages that are spam but that were not tagged (or didn't score high enough) into the Spam/ToBeLearnedSpam folder.  Within 24 hours, the messages will be learned by SpamAssassin as being spam, and they will be moved to the Spam/LearnedSpam folder, where they will wait for 1 week and then be automatically deleted.

For the first few hundred messages, it will be especially helpful for you to put spam and non-spam samples in the appropriate ToBeLearned* folder - this speeds up the process of training the filter.