Q: I want to send you a (spam) sample to analyse, etc.

A: Go ahead, but please send it as a gzip or zip attachment.

Q: Does clapf support virtual users?

A: Yes, however, it requires a little configuration.

Let's say you have the following postfix configuration in main.cf and the virtual stuff is stored in MySQL tables:

virtual_mailbox_domains = proxy:mysql:/etc/postfix/mysql-vdomains.cf
virtual_mailbox_base = /var/vmail
virtual_mailbox_maps = proxy:mysql:/etc/postfix/mysql-aliases.cf
virtual_uid_maps = static:1004
virtual_gid_maps = static:104

Create /etc/postfix/mysql-vdomains.cf like this:

user = clapf
password = verystrongsecret
dbname = clapf

query = SELECT domain FROM t_domain WHERE domain='%s'

Create /etc/postfix/mysql-aliases.cf like this:

user = clapf password = verystrongsecret dbname = clapf query = SELECT LOWER(CONCAT(substring_index(substring_index('%s', '@', -1), '.', -2), "/", substring_index('%s', '@', 1), "/")) FROM user, t_email WHERE user.uid=t_email.uid AND email='%s'

This will return the virtual directory in the form of yourdomain.com/user/, eg. aaa.fu/aa/ for aa@aaa.fu.

Q: How do I create a dedicated filtering box and forward all my email to my Exchange server?

A: Create the mysql .cf files like above, then create a transport map file

main.cf:

virtual_mailbox_domains = proxy:mysql:/etc/postfix/mysql-vdomains.cf
virtual_mailbox_maps = proxy:mysql:/etc/postfix/mysql-aliases.cf
transport_maps = proxy:hash:/etc/postfix/transport

/etc/postfix/transport:

*               smtp:[exchange.aaa.fu]

Q: How do I assign an arbitrary virtual path to my users?

A: Extend the 'user' table to hold the virtual path value, eg.

mysql>alter table user add column vdir char(255) default null;

Modify user entries like this:

update user set vdir = '' where username='aaa';

Create /etc/postfix/mysql-aliases.cf like this:

user = clapf password = verystrongsecret dbname = clapf query = SELECT vdir FROM user WHERE email='%s'

Q: Does spamdrop support virtual users?

A: Yes, however, it also requires a little configuration.

We will configure postfix to use maildrop as the local delivery agent

main.cf:

maildrop_destination_recipient_limit = 1
virtual_mailbox_domains = aaaa.fu
virtual_transport = maildrop
virtual_mailbox_maps = hash:/etc/postfix/virtual_mailbox

virtual_mailbox has all the valid email addresses:

jim@aaaa.fu     ok
joe@aaaa.fu	ok
....

master.cf:

maildrop unix - n n - - pipe
   flags=ODRhu user=clapf:clapf argv=/usr/local/bin/maildrop /etc/maildroprc 
   -d ${user}@${nexthop} ${extension} ${recipient} ${user} ${nexthop}

/etc/maildroprc:

xfilter "/usr/local/bin/spamdrop -r $4"

VMAILDIR=/var/vmail/domains
DOMAINDIR=$VMAILDIR/$6
MAILDIR=$DOMAINDIR/$5/

`[ -d $DOMAINDIR ]`
if ( $RETURNCODE == 1 )
{
        A=`/bin/mkdir $DOMAINDIR`

        `[ -d $MAILDIR/cur ]`
        if( $RETURNCODE == 1 )
        {
                B=`/usr/local/bin/maildirmake $MAILDIR`
        }

}

to "$MAILDIR"

Finally set up proper permission on /etc/maildroprc:

chown clapf:clapf /etc/maildroprc
chmod 600 /etc/maildroprc

Important! The user 'clapf' needs a valid shell, otherwise it cannot execute the commands above.

Q: How to setup virtual users with LDAP?

A: Set the following in main.cf:

virtual_mailbox_domains = mail.aaaa.fu
virtual_mailbox_base = /var/vmail
virtual_mailbox_maps = ldap:/etc/postfix/ldap-aliases.cf
virtual_uid_maps = static:1004
virtual_gid_maps = static:104

Create /etc/postfix/ldap-aliases.cf like this:

server_host = localhost
search_base = ou=billing, dc=aaaa, dc=fu
version = 3
query_filter = (|(mail=%s)(mailAlternateAddress=%s))
result_attribute = mailMessageStore
result_format  =  %s/Maildir/

Then add the qmail.schema to your LDAP configuration, and add your users to the LDAP server. An example ldif file is shown below.

dn: dc=aaaa,dc=fu
dc: aaaa
objectClass: top
objectClass: dcObject
objectClass: organization
o: aaaa.fu

dn: ou=billing,dc=aaaa,dc=fu
ou: billing
objectClass: top
objectClass: organizationalUnit

dn: cn=jim,ou=billing,dc=aaaa,dc=fu
cn: jim
sn: whatever
objectClass: top
objectClass: person
objectClass: qmailUser
objectClass: qmailGroup
uid: 1
mail: jim@aaaa.fu
mailAlternateAddress:
mailMessageStore: x
filtersender:
blackList:
policyGroupId: 0
isAdmin: 0
userPassword: thepassword

Q: How to prevent spam to reach users' inboxes?

A: Set the spaminess_oblivion_limit somewhere between the value of spam_overall_limit and 1, eg. 0.99. Then clapf will silently drop any spam message with a spam probability value greater than 99%. Please note that these spam messages will still get to the users' queue directory, so they can access their spam through the web UI, but their inbox will be free of spam.

Note that you also need to compile clapf with the --with-store=fs configure options.

Q: Why can't I train by forwarding an email using Outlook?

A: Outlook (not Outlook Express) has a nasty habit arbitrarily removing some header elements needed for clapf to process the training request.

Workaround: specify the --enable-outlook-hack configure option forcing clapf to put its data to the Received: lines.

Q: How to disable spam check for outgoing emails?

A: Set use_antispam=0 in clapf.conf. Then create a new policy group and set use_antispam=1. Finally update your users to be in the new policy group. This way clapf does spam checking for incoming emails only.

Q: What happens if I mistakenly train a message as ham, then as spam?

A: The accuracy of any statistical anti-spam application mostly depends on the quality of the token database. Although it's not a fatal problem if you happen to do this, but be aware, it may result a less accurate operation in some cases.

Q: How could I figure out what this application does?

A: If you are curious, set verbosity=5 in clapf.conf, then send a HUP signal to the clapf daemon, and it will syslog a lot of stuff.

If you want to know why a single message is considered as spam (or ham) then use the spamdrop utility against a single RFC-822 format message as follows:

# test with your current unix uid as the clapf uid
spamdrop -D < messagefile

#test for jim@aaaa.fu
spamdrop -D -r jim@aaaa.fu < messagefile

This will print out the message as clapf sees it, the tokens participated in the statistical decision, and other stuff.

Q: How can I set up the queue directory on a different partition or different computer?

A: specify the --with-store=nfs configure option. In case of a remote computer mount the exported partition under your queue directory (/var/lib/clapf/queue).

Q: I have Outlook Express mailbox. How can I create a token database?

A: Try MailNavigator that can read OE mailboxes and export them as an mbox.

“When you start it up, do File→Load External Mailbox… Point the browser window at the OE inbox.dbx file, normally in Documents and Settings \currentuser\Local Settings\Application Data\Identities\{bunchaglorp} \Microsoft\Outlook Express. You should see your inbox (or whatever folder you loaded) contents in MailNavigator. Then do Message→Select All, then Message→Save As… pick a file name and location, and select file type RFC822-text file… et voila, you have an mbox!”

Source: http://mail.python.org/pipermail/spambayes/2003-March/004128.html