11 Postfix

These instructions need a lot of work.

11.1 All Machines

1. Create a postfix user and groups
   # groupadd -g 220 postfix 
   # groupadd -g 225 postdrop 
   # useradd -u 220 -g postfix -d /dev/null -s /bin/false postfix
2. Remove sendmail. There may be dependencies with mutt and fetchmail so either use the -no-deps option to rpm or remove mutt and fetchmail.
   # rpm -e mutt 
   # rpm -e fetchmail 
   # rpm -e sendmail
3. Make and Install
   # make 
   # make install
4. If necessary link /usr/sbin/sendmail to /usr/lib/sendmail (remove or rename old sendmail if necessary):
   # cd /usr/sbin
   # ln -s /usr/lib/sendmail sendmail
5. Copy or create the postfix startup script (Sec: 11.6) to the init directory
6. Set the service to start at boot
   # chkconfig postfix add 
   # chkconfig postfix -list
7. Copy or modify the configuration for Send Only (Sec: 11.2) or Server (Sec: 11.3) as appropiate.
8. Start the service
   # service postfix start

11.2 Send Only

1. Comment out smtp in /etc/postfix/master.cf to prevent the machine from receiving mail.
2. Copy or create the send-only aliases file, /etc/aliases.
3. Create the aliases database
   # newaliases
4. Send a test message

11.3 Mail Server

1. Copy over main.cf and master.cf
2. If using sendmail type aliases, copy or create the /etc/aliases file. If using virtual_maps create an empty aliases file.
   # touch /etc/aliases
3. Create or copy : access, canonical, relocated, transport, and virtual.

11.3.1 Emptying mail queue

1. $ postconf -e 'maximal_queue_lifetime=0s'
   $ postfix reload
   $ postfix flush
   $ ... wait for queue to drain ...
   $ postconf -e 'maximal_queue_lifetime=5d'
   $ postfix reload

11.4 Special Considerations

11.4.1 Local Delivery when forwarding

1. In /etc/postfix/main.cf 
   mydestination = $myhostname localhost.$mydomain 
   relay_domains = $mydomain
2. In /etc/postfix/virtual set the local user(s) to:
   <localuser>@totalflood.com    <localuser>@localhost.totalflood.com
3. In /etc/postfix/transport set the local name to local delivery
   localhost.totalflood.com    local: 
   mail.totalflood.com         local:

11.5 Configuration Notes

When setting up smtpd restrictions remember:

• client = hostname/ip
• sender = sender email adress
• recipient = recipient email adress
• smtpd_client_restrictions = restrict based on client IP address or reverse DNS lookup of that IP address (Only if forward DNS lookup give back same IP address)
• smtpd_helo_restrictions = restrict based on HELO/EHLO sent by client, or any restriction appropriate to smtpd_client_restrictions
• smtpd_sender_restrictions = restrict based on MAIL FROM email address, or any restriction appropriate to either smtpd_client_restrictions or smtpd_helo_restrictions
• smtpd_recipient_restrictions = restrict based on RCPT TO email address, or any restriction appropriate to any other smtpd_*_restrictions line.

11.6 Postfix init script

#!/bin/sh 
# 
# postfix This shell script takes care of starting and stopping 
# postfix. 
# 
# chkconfig: 2345 80 30 
# 
# description: Postfix is a Mail Transport Agent, which is the program 
# that moves mail from one machine to another. 
# Source function library. 
. /etc/rc.d/init.d/functions 
 
# Source networking configuration. 
. /etc/sysconfig/network 
 
# Check that networking is up. 
[ ${NETWORKING} = "no" ] && exit 0 
 
[ -f /usr/sbin/postfix ] || exit 0 
 
# See how we were called. 
case "$1" in 
   start) 
      # Start daemons. 
      echo -n "Starting postfix: " 
      newaliases 
      for I in access canonical relocated transport virtual 
      do 
      if [ -f /etc/postfix/$I ] ; then 
         /usr/sbin/postmap hash:/etc/postfix/$I < /etc/postfix/$I 
      fi 
      done 
      /usr/sbin/postfix start 2>/dev/null 
      echo postfix 
      touch /var/lock/subsys/postfix 
      ;; 
   stop) 
      # Stop daemons. 
      echo -n "Shutting down postfix: " 
      /usr/sbin/postfix stop 2>/dev/null 
      echo postfix 
      rm -f /var/lock/subsys/postfix 
      ;; 
   restart) 
      $0 stop 
      $0 start 
      ;; 
   reload) 
      /usr/sbin/postfix reload 
      ;; 
   status) 
      status master 
      ;; 
   *) 
      echo "Usage: $0 {start|stop|restart|reload|status}" 
      exit 1 
   esac 
 
exit 0