I am using FC11, each account can have their own sieve filter.  The default is ${HOME}/.dovecot.sieve which is a text file.

Here is a snippet of my .dovecot.sieve file.

NOTE: you need the sieve plugins (envelope, subaddress, regex, relational)


require ["reject", "fileinto", "envelope", "subaddress", "regex", "relational"];
if  anyof (
header :contains ["Return-path"] "firewall-wizards-bounces@listserv.icsalabs.com",
header :contains ["List-Id"] "Firewall Wizards Security Mailing List",
header :contains ["List-Post"] "mailto:firewall-wizards@listsserv..icsalabs.com") {
fileinto "lists.firewall";
} elsif anyof (
header :contains ["X-Mailing-List"] "pgsql-general",
header :contains ["List-ID"] "pgsql-general.postgresql.org",
header :contains ["X-Mailing-List"] "pgsql-performance",
header :contains ["List-ID"] "pgsql-performance.postgresql.org") {
fileinto "lists.postgresql";
} elsif anyof (
header :contains ["X-BeenThere"] "rubyonrails-talk",
header :contains ["List-ID"] "rubyonrails-talk.googlegroups.com") {
fileinto "lists.rails";
} else {
# The rest goes into INBOX
# default is "implicit keep", we do it explicitly here
keep;
}