Virtual Users And Domains With Postfix, Courier, MySQL And SquirrelMail (CentOS 6.2 x86_64) - Page 5

13 Install Razor, Pyzor And DCC And Configure SpamAssassin

Razor, Pyzor and DCC are spamfilters that use a collaborative filtering network. To install Razor and Pyzor, run

yum install perl-Razor-Agent pyzor

Then initialize both services:

chmod -R a+rX /usr/share/doc/pyzor-0.5.0 /usr/bin/pyzor /usr/bin/pyzord
 chmod -R a+rX /usr/lib/python2.6/site-packages/pyzor
 su -m amavis -c 'pyzor --homedir /var/spool/amavisd discover'
 su -m amavis -c 'razor-admin -home=/var/spool/amavisd -create'
 su -m amavis -c 'razor-admin -home=/var/spool/amavisd -register'

Then we install DCC as follows:

cd /tmp
 wget http://www.dcc-servers.net/dcc/source/dcc-dccproc.tar.Z
 tar xzvf dcc-dccproc.tar.Z
 cd dcc-dccproc-1.3.141
 ./configure --with-uid=amavis
 make
 make install
 chown -R amavis:amavis /var/dcc
 ln -s /var/dcc/libexec/dccifd /usr/local/bin/dccifd

Now we have to tell SpamAssassin to use these three programs. Edit /etc/mail/spamassassin/local.cf so that it looks like this:

vi /etc/mail/spamassassin/local.cf

# These values can be overridden by editing ~/.spamassassin/user_prefs.cf
# (see spamassassin(1) for details)

# These should be safe assumptions and allow for simple visual sifting
# without risking lost emails.

#required_hits 5
#report_safe 0
#rewrite_header Subject [SPAM]

# dcc
use_dcc 1
dcc_path /usr/local/bin/dccproc

#pyzor
use_pyzor 1
pyzor_path /usr/bin/pyzor

#razor
use_razor2 1
razor_config /var/spool/amavisd/razor-agent.conf

#bayes
use_bayes 1
use_bayes_rules 1
bayes_auto_learn 1

Then we must enable the DCC plugin in SpamAssassin. Open /etc/mail/spamassassin/v310.pre and uncomment the loadplugin Mail::SpamAssassin::Plugin::DCC line:

vi /etc/mail/spamassassin/v310.pre

[...]
# DCC - perform DCC message checks.
#
# DCC is disabled here because it is not open source.  See the DCC
# license for more details.
#
loadplugin Mail::SpamAssassin::Plugin::DCC
[...]

You can check your SpamAssassin configuration by executing:

spamassassin --lint

It shouldn't show any errors.

Run

/etc/init.d/amavisd restart

afterwards.

Now we update our SpamAssassin rulesets as follows:

sa-update --no-gpg

We create a cron job so that the rulesets will be updated regularly. Run

crontab -e

to open the cron job editor. Create the following cron job:

23 4 */2 * * /usr/bin/sa-update --no-gpg &> /dev/null

This will update the rulesets every second day at 4.23h.

14 Quota Exceedance Notifications

If you want to get notifications about all the email accounts that are over quota, then create the file /usr/local/sbin/quota_notify:

cd /usr/local/sbin/
 vi quota_notify

#!/usr/bin/perl -w

# Author <[email protected]>
#
# This script assumes that virtual_mailbox_base in defined
# in postfix's main.cf file. This directory is assumed to contain
# directories which themselves contain your virtual user's maildirs.
# For example:
#
# -----------/
#            |
#            |
#    home/vmail/domains/
#        |          |
#        |          |
#  example.com/  foo.com/
#                   |
#                   |
#           -----------------
#           |       |       |
#           |       |       |
#         user1/   user2/  user3/
#                           |
#                           |
#                        maildirsize
#

use strict;

my $POSTFIX_CF = "/etc/postfix/main.cf";
my $MAILPROG = "/usr/sbin/sendmail -t";
my $WARNPERCENT = 80;
my @POSTMASTERS = ('[email protected]');
my $CONAME = 'My Company';
my $COADDR = '[email protected]';
my $SUADDR = '[email protected]';
my $MAIL_REPORT = 1;
my $MAIL_WARNING = 1;

#get virtual mailbox base from postfix config
open(PCF, "< $POSTFIX_CF") or die $!;
my $mboxBase;
while (<PCF>) {
   next unless /virtual_mailbox_base\s*=\s*(.*)\s*/;
   $mboxBase = $1;
}
close(PCF);

#assume one level of subdirectories for domain names
my @domains;
opendir(DIR, $mboxBase) or die $!;
while (defined(my $name = readdir(DIR))) {
   next if $name =~ /^\.\.?$/;        #skip '.' and '..'
   next unless (-d "$mboxBase/$name");
   push(@domains, $name);
}
closedir(DIR);
#iterate through domains for username/maildirsize files
my @users;
chdir($mboxBase);
foreach my $domain (@domains) {
        opendir(DIR, $domain) or die $!;
        while (defined(my $name = readdir(DIR))) {
           next if $name =~ /^\.\.?$/;        #skip '.' and '..'
           next unless (-d "$domain/$name");
      push(@users, {"$name\@$domain" => "$mboxBase/$domain/$name"});
        }
}
closedir(DIR);

#get user quotas and percent used
my (%lusers, $report);
foreach my $href (@users) {
   foreach my $user (keys %$href) {
      my $quotafile = "$href->{$user}/maildirsize";
      next unless (-f $quotafile);
      open(QF, "< $quotafile") or die $!;
      my ($firstln, $quota, $used);
      while (<QF>) {
         my $line = $_;
              if (! $firstln) {
                 $firstln = 1;
                 die "Error: corrupt quotafile $quotafile"
                    unless ($line =~ /^(\d+)S/);
                 $quota = $1;
            last if (! $quota);
            next;
         }
         die "Error: corrupt quotafile $quotafile"
            unless ($line =~ /\s*(-?\d+)/);
         $used += $1;
      }
      close(QF);
      next if (! $used);
      my $percent = int($used / $quota * 100);
      $lusers{$user} = $percent unless not $percent;
   }
}

#send a report to the postmasters
if ($MAIL_REPORT) {
   open(MAIL, "| $MAILPROG");
   select(MAIL);
   map {print "To: $_\n"} @POSTMASTERS;
   print "From: $COADDR\n";
   print "Subject: Daily Quota Report.\n";
   print "DAILY QUOTA REPORT:\n\n";
   print "----------------------------------------------\n";
   print "| % USAGE |            ACCOUNT NAME          |\n";
   print "----------------------------------------------\n";
   foreach my $luser ( sort { $lusers{$b} <=> $lusers{$a} } keys %lusers ) {
      printf("|   %3d   | %32s |\n", $lusers{$luser}, $luser);
      print "---------------------------------------------\n";
   }
        print "\n--\n";
        print "$CONAME\n";
        close(MAIL);
}

#email a warning to people over quota
if ($MAIL_WARNING) {
        foreach my $luser (keys (%lusers)) {
           next unless $lusers{$luser} >= $WARNPERCENT;       # skip those under quota
           open(MAIL, "| $MAILPROG");
           select(MAIL);
           print "To: $luser\n";
      map {print "BCC: $_\n"} @POSTMASTERS;
           print "From: $SUADDR\n";
           print "Subject: WARNING: Your mailbox is $lusers{$luser}% full.\n";
           print "Reply-to: $SUADDR\n";
           print "Your mailbox: $luser is $lusers{$luser}% full.\n\n";
           print "Once your e-mail box has exceeded your monthly storage quota\n";
      print "your monthly billing will be automatically adjusted.\n";
      print "Please consider deleting e-mail and emptying your trash folder to clear some space.\n\n";
           print "Contact <$SUADDR> for further assistance.\n\n";
           print "Thank You.\n\n";
           print "--\n";
           print "$CONAME\n";
           close(MAIL);
        }
}

Make sure that you adjust the variables at the top (especially the [email protected] email address).

We must make the file executable:

chmod 755 quota_notify

Run

crontab -e

to create a cron job for that script:

0 0 * * * /usr/local/sbin/quota_notify &> /dev/null

15 Test Postfix

To see if Postfix is ready for SMTP-AUTH and TLS, run

telnet localhost 25

After you have established the connection to your Postfix mail server type

ehlo localhost

If you see the lines

250-STARTTLS 

and

250-AUTH PLAIN LOGIN 

everything is fine.

[root@server1 sbin]# telnet localhost 25
Trying ::1...
Connected to localhost.
Escape character is '^]'.
220 server1.example.com ESMTP Postfix
<-- ehlo localhost
250-server1.example.com
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-STARTTLS
250-AUTH PLAIN LOGIN
250-AUTH=PLAIN LOGIN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
<-- quit
221 2.0.0 Bye
Connection closed by foreign host.
[root@server1 sbin]#

Type

quit

to return to the system's shell.

16 Populate The Database And Test

To populate the database you can use the MySQL shell:

mysql -u root -p

USE mail;

At least you have to create entries in the tables domains and users:

INSERT INTO `domains` (`domain`) VALUES ('example.com');
 INSERT INTO `users` (`email`, `password`, `quota`) VALUES ('[email protected]', ENCRYPT('secret'), 10485760);

(Please take care you use the ENCRYPT syntax in the second INSERT statement in order to encrypt the password!)

If you want to make entries in the other two tables, that would look like this:

INSERT INTO `forwardings` (`source`, `destination`) VALUES ('[email protected]', '[email protected]');
 INSERT INTO `transport` (`domain`, `transport`) VALUES ('example.com', 'smtp:mail.example.com');

To leave the MySQL shell, type

quit;

For most people it is easier if they have a graphical front-end to MySQL; therefore you can also use phpMyAdmin (in this example under http://192.168.0.100/phpMyAdmin/ or http://server1.example.com/phpMyAdmin/) to administrate the mail database. Again, when you create a user, go sure that you use the ENCRYPT function to encrypt the password:

I do not think I have to explain the domains and users table further.

The forwardings table can have entries like the following:

The transport table can have entries like these:

See

man transport

for more details.

Please keep in mind that the order of entries in the transport table is important! The entries will be followed from the top to the bottom.

Important: Postfix uses a caching mechanism for the transports, therefore it might take a while until you changes in the transport table take effect. If you want them to take effect immediately, run

postfix reload

after you have made your changes in the transport table.

17 Send A Welcome Email For Creating Maildir

When you create a new email account and try to fetch emails from it (with POP3/IMAP) you will probably get error messages saying that the Maildir doesn't exist. The Maildir is created automatically when the first email arrives for the new account. Therefore it's a good idea to send a welcome email to a new account.

First, we install the mailx package:

yum install mailx

To send a welcome email to [email protected], we do this:

mailx [email protected]

You will be prompted for the subject. Type in the subject (e.g. Welcome), then press ENTER, and in the next line type your message. When the message is finished, press ENTER again so that you are in a new line, then press CTRL+D:

[root@server1 ~]# mailx [email protected]
Subject: Welcome <-- ENTER
Welcome! Have fun with your new mail account. <-- ENTER
<-- CTRL+D
EOT
[root@server1 ~]#