The TCC's current implementation of Spamassassin is through a sendmail mail filter. The mail filter checks to see if the incoming mail is spam or not. Unlike other implementations of Spamassassin, the mail filter will not rewrite the mail's header.
When Spamassassin looks at your mail, it is assigned a score based on tests it runs on the mail. If the score exceeds a number called the spam score limit, the mail is considered spam and will not be delivered to your mailbox. The TCC's default spam score limit is 10.
The filtering that the TCC does may be sufficient for you. If not, see Section 4, “ When the TCC mail filter is not enough: filtering with procmail ”.