These instructions are still in BETA. Separate keys need to be setup. /etc/postfix2/main.cf needs to be checked.
Sender-based routing allows delivery actions on email to be made based on the sending address. This makes it possible for each Gmail and or Comcast account to have separate authentication rules. In summary, your home Postfix system can support Gmail and Comcast accounts for all of your family and friends.
You will need an initial postfix setup. To get the initial setup please reference and follow Gmail on Home Linux Box using Postfix and Fetchmail, since this article builds on it. Please make sure you have that initial setup working. The first Postfix instance will change from the previous article to relay mail to the second Postfix instance on a separate IP address, with a distinguished hostname. The second instance will log entries as "postfix2" for easier problem tracking. Outgoing mail can still be configured on the original IP address to accommodate firewall rules. All of this is explained with examples below. Please read on.
1.1 Second IP (ifcfg-eth0:1)
A second instance of Postfix will run on it's own IP address. Therefore, you will need to add an additional IP address to your server's NIC (Network Interface Card). If you're running Red Hat or Fedora, you will add the file "/etc/sysconfig/network-scripts/ifcfg-eth0:1". The simplest way to do this is by copying the existing ifcfg-eth0 file.
$ cp /etc/sysconfig/network-scripts/ifcfg-eth0 /etc/sysconfig/network-scripts/ifcfg-eth0:1
Edit this file and change the IP address to the second address. My second IP address is 192.168.1.82.Take a look at my two files (ifcfg-eth0, ifcfg-eth0:1 ). Note both settings IPADDR=192.168.1.82 and DEVICE=eth0:1 in ifcfg-eth0:1. Yes, the filename does have a ":" colon in it.
1.2 Modify /etc/hosts
Bind the name to the IP address. This can be done by editing the /etc/hosts file. Below is the file I used to bind the name squeezel2.squeezel.com to the second IP address 192.168.1.81.
cat /etc/hosts 192.168.1.81 squeezel.squeezel.com squeezel 192.168.1.82 squeezel2.squeezel.com
1.3 Restart Network Services
The following command, executed as root, will restart the network services.
$ /etc/init.d/network restart
1.4 Confirm 2nd IP
At this stage both IP addresses should be working on the card. Check this with the ifconfig command.
$ ifconfig eth0 Link encap:Ethernet HWaddr 00:11:11:8A:BE:3F inet addr:192.168.1.81 Bcast:192.168.99.255 Mask:255.255.252.0 inet6 addr: fe80::211:11ff:fe8a:be3f/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:264369 errors:0 dropped:0 overruns:0 frame:0 TX packets:243745 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:59584619 (56.8 MiB) TX bytes:34479618 (32.8 MiB) Interrupt:169 eth0:1 Link encap:Ethernet HWaddr 00:11:11:8A:BE:3F inet addr:192.168.1.82 Bcast:192.168.3.255 Mask:255.255.252.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 Interrupt:169 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:163487 errors:0 dropped:0 overruns:0 frame:0 TX packets:163487 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:107287251 (102.3 MiB) TX bytes:107287251 (102.3 MiB)
You can use the current copy of postfix install, everything under "/etc/postfix", as a starting point for creating the second instance.
$ cp -rp /etc/postfix /etc/postfix2
Above the "-r" performs a recursive copy of any subdirectories and "-p" preserves mode, ownership, and timestamps of the files. The mode and ownership should be preserved.
2.1 /etc/postfix2/main.cf Initial Modifications
The following entries are made at the end of the /etc/postfix2/main.cf file.
# DNS name of second IP address inet_interfaces = squeezel2.squeezel.com myhostname = squeezel2.squeezel.com queue_directory = /var/spool/postfix2 # Inform 2nd instance of other version alternative_config_directories = /etc/postfix smtp_bind_address = 192.168.1.81 # Separate Logging syslog_name=postfix2 # Make sure settings go to /etc/postfix2 transport_maps = hash:/etc/postfix2/transport
The DNS name, use your specific values in /etc/hosts, should be the value assigned to inet_interfaces. The queue_directory is necessary so that the spool files for the second instance of Postfix do not conflict with the first.
The smtp_bind_address parameter forces outgoing mail from the second Postfix instance to bind to the original IP address. This can be a convenience, since existing Firewall rules can be accommodated. However, the second IP address could have been used instead. The syslog_name parameter prefaces log entries with "postfix2".
2.2 Create Second Spool Directory
The next step is to create an additional spool directory. In the above step note the queue_directory = /var/spool/postfix2 change, which is necessary for the command below to work.
$ mkdir /var/spool/postfix2 $ postfix -c /etc/postfix2 check
After running the step above, you should have the following contents in this directory.
$ ls -l /var/spool/postfix2 total 112 drwx------ 2 postfix root 4096 Nov 1 19:43 active drwx------ 2 postfix root 4096 Nov 1 19:43 bounce drwx------ 2 postfix root 4096 Nov 1 19:43 corrupt drwx------ 2 postfix root 4096 Nov 1 19:43 defer drwx------ 2 postfix root 4096 Nov 1 19:43 deferred drwx------ 2 postfix root 4096 Nov 1 19:43 flush drwx------ 2 postfix root 4096 Nov 1 19:43 hold drwx------ 2 postfix root 4096 Nov 1 19:43 incoming drwx-wx--- 2 postfix postdrop 4096 Nov 1 19:43 maildrop drwxr-xr-x 2 root root 4096 Nov 1 19:43 pid drwx------ 2 postfix root 4096 Nov 1 19:43 private drwx--x--- 2 postfix postdrop 4096 Nov 1 19:43 public drwx------ 2 postfix root 4096 Nov 1 19:43 saved drwx------ 2 postfix root 4096 Nov 1 19:43 trace
2.3 Create Second Start-up Script
The following is the /etc/init.d/postfix2 start-up script for the second instance. If you're using Red Hat or Fedora, you can configure this to start automatically with the following, executed as root.
$ wget http://ftp1.sourceforge.net/souptonuts/postfix2.txt -O /etc/init.d/postfix2 $ chmod 2744 /etc/init.d/postfix2 $ chkconfig --add postfix2
The first step above saves the file as postfix2. The next step makes the file executable. The third step configures the file to startup when your system boots. To check that the following steps, execute the following:
$ chkconfig --list postfix2 postfix2 0:off 1:off 2:on 3:on 4:on 5:on 6:off
As you can see above, postfix2 will run on levels 2,3,4 and 5. This is fine, but you only need levels 3 and 5. It's easy enough to make the change.
$ chkconfig --level 01246 postfix2 off
Take a look at postfix2 at the line "chkconfig: 2345 80 30", since the change could have been made here as well to "chkconfig: 35 80 30". The 80 and 30 refer to the start priority and stop priority respectively.
Further modifications are needed in main.cf so that the routing path will be determined by the sender, hence the name sender-based routing. For example, the Linux account zchirico, the sender, should connect and authenticate as firstname.lastname@example.org with password zP3ssw04d.
Configure the second instances to support sender-based routing.
# Changes in /etc/postfix2/main.cf sender_based_routing = yes3.2 /etc/postfix2/master.cf
If you copied the /etc/postfix/master.cf from the previous article, you should remove the "-o smtp_generic_maps=" switch in the second instance. Below is the correct output of "/etc/postfix2/master.cf" for 4 accounts. Please view the complete /etc/postfix2/master.cf.
relay unix - - n - - smtp -o fallback_relay= smtp_act1 unix - - n - - smtp -o smtp_sasl_password_maps=hash:/etc/postfix2/sasl_passwd_act1 smtp_act2 unix - - n - - smtp -o smtp_sasl_password_maps=hash:/etc/postfix2/sasl_passwd_act2 smtp_act3 unix - - n - - smtp -o smtp_sasl_password_maps=hash:/etc/postfix2/sasl_passwd_act3 smtp_act4 unix - - n - - smtp -o smtp_sasl_password_maps=hash:/etc/postfix2/sasl_passwd_act4
There will be 4 accounts setup as follows:
|smtp_sasl_password_maps||Linux Name||Email Name||Password|
Note that the first 3 accounts map to Gmail and the forth account is a Comcast account. The account information will be put into the respective sasl_passwd_act(N) files. See below.
#/etc/postfix2/sasl_passwd_act1 [smtp.gmail.com] email@example.com:Zp3ssw04
As you will see with each file, you need to run postmap and change the permissions on these files.
$ cd /etc/postfix2 $ postmap sasl_passwd_act1 $ chown root.postfix sasl_passwd* $ chmod 0640 sasl_passwd*
#/etc/postfix2/sasl_passwd_act2 [smtp.gmail.com] firstname.lastname@example.org:Ap3ssw04
$ cd /etc/postfix2 $ postmap sasl_passwd_act2 $ chown root.postfix sasl_passwd* $ chmod 0640 sasl_passwd*
#/etc/postfix2/sasl_passwd_act3 [smtp.gmail.com] email@example.com:Lp3ssw04
$ cd /etc/postfix2 $ postmap sasl_passwd_act3 $ chown root.postfix sasl_passwd* $ chmod 0640 sasl_passwd*
#/etc/postfix2/sasl_passwd_act4 [smtp.comcast.net] firstname.lastname@example.org:Lp3ssw04
$ cd /etc/postfix2 $ postmap sasl_passwd_act4 $ chown root.postfix sasl_passwd4* $ chmod 0640 sasl_passwd4*
The transport map in the second postfix instance will need to be modified.
#/etc/postfix2/transport email@example.com smtp_act1:[smtp.gmail.com] firstname.lastname@example.org smtp_act2:[smtp.gmail.com] email@example.com smtp_act3:[smtp.gmail.com] firstname.lastname@example.org smtp_act4:[smtp.comcast.net]
Make sure to run postmap on this file.
$ cd /etc/postfix2 $ postmap transport
The first instance of Postfix needs to be modified.
4.1 /etc/postfix/main.cf Modifications
The first instance of Postfix relays email to the second instance, with the command below.
#/etc/postfix/main.cf relayhost = [squeezel2.squeezel.com] inet_interfaces = squeezel.squeezel.com myhostname = squeezel.squeezel.com alternative_config_directories = /etc/postfix2
The generic file in the first Postfix instance will be used to rewrite the addresses.
# /etc/postfix/generic email@example.com firstname.lastname@example.org email@example.com firstname.lastname@example.org email@example.com firstname.lastname@example.org email@example.com firstname.lastname@example.org
Run postmap on this file.
$ cd /etc/postfix $ postmap generic
Take out specific reference to Comcast or Gmail in the first Postfix transport map.
At this stage postfix and postfix2 should be restarted.
$ /etc/init.d/postfix2 $ /etc/init.d/postfix
Below is the example .fetchmailrc file for zchirico to access the email@example.com account. Note that the smtphost setting (smtphost squeezel.squeezel.com) references the first Postfix instance.
# # # Sample .fetchmailrc file for Gmail # # Check mail every 90 seconds set daemon 90 set syslog set postmaster zchirico poll pop.gmail.com with proto POP3 user 'firstname.lastname@example.org' \ with pass "Zp3ssw04" is 'zchirico' here \ options ssl sslcertck sslcertpath '/home/zchirico/certs/.certs' # Note smtphost is First Postfix instance smtphost squeezel.squeezel.com
You will need to download Goole's certificates. Reference section 5 in the tutorial Gmail on Home Linux Box using Postfix and Fetchmail
Review the logs, and check the configuration of each instance using the "-c" option with the postconf command as follows:
$ postconf -c /etc/postfix2
The above command will give a listing of all options.
It's possible to defer email only on the second instance as follows:
$ postconf -c /etc/postfix2 -e "defer_transports=smtp" $ postfix -c /etc/postfix2 reload
Now, send an email and the message will be defered. You'll see it in the logs.
$ tail /var/log/maillog Nov 6 20:14:34 laptop postfix2/qmgr: 26F43AB038F: from=<email@example.com>, size=620, nrcpt=1 (queue active) Nov 6 20:14:34 laptop postfix2/qmgr: 26F43AB038F: to=<firstname.lastname@example.org>, relay=none, delay=0, status=deferred (delivery temporarily suspended: deferred transport)
You can see the message in the queue with the following command.
$ find /var/spool/postfix2/deferred/ -iname '*' -type f /var/spool/postfix2/deferred/2/26F43AB038F
It's also possible to see the contents of that email too with the postcat command.
$ postcat /var/spool/postfix2/deferred/2/26F43AB038F # postcat /var/spool/postfix2/deferred/2/26F43AB038F *** ENVELOPE RECORDS /var/spool/postfix2/deferred/2/26F43AB038F *** message_size: 620 333 1 0 message_arrival_time: Sun Nov 6 20:14:34 2005 named_attribute: rewrite_context=remote sender: email@example.com named_attribute: client_name=squeezel.squeezel.com named_attribute: client_address=192.168.1.81 named_attribute: message_origin=squeezel.squeezel.com[192.168.1.81] named_attribute: helo_name=squeezel.squeezel.com named_attribute: protocol_name=ESMTP original_recipient: firstname.lastname@example.org recipient: email@example.com *** MESSAGE CONTENTS /var/spool/postfix2/deferred/2/26F43AB038F *** Received: from squeezel.squeezel.com (squeezel.squeezel.com [192.168.1.81]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by squeezel2.squeezel.com (Postfix) with ESMTP id 26F43AB038F for <firstname.lastname@example.org>; Sun, 6 Nov 2005 20:14:34 -0500 (EST) Received: by squeezel.squeezel.com (Postfix, from userid 504) id B1D24BB868C; Sun, 6 Nov 2005 20:14:33 -0500 (EST) To: email@example.com Subject: test more Message-Id: <20051107011433.B1D24BB868C@squeezel.squeezel.com> Date: Sun, 6 Nov 2005 20:14:33 -0500 (EST) From: firstname.lastname@example.org this is a message *** HEADER EXTRACTED /var/spool/postfix2/deferred/2/26F43AB038F *** *** MESSAGE FILE END /var/spool/postfix2/deferred/2/26F43AB038F ***
To instruct Postfix to deliver that message, execute the following commands.
$ postconf -c /etc/postfix2 -e "defer_transports =" $ postfix -c /etc/postfix2 reload $ postfix -c /etc/postfix2 flush
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Mike Chirico, a father of triplets (all girls) lives outside of
Philadelphia, PA, USA. He has worked with Linux since 1996, has a Masters
in Computer Science and Mathematics from Villanova University, and has
worked in computer-related jobs from Wall Street to the University of
Pennsylvania. His hero is Paul Erdos, a brilliant number theorist who was
known for his open collaboration with others.
Mike's notes page is souptonuts. For open source consulting needs, please send an email to email@example.com. All consulting work must include a donation to SourceForge.net.