How to Enable Logging for Email Subject Fields in Postfix Maillog

Postfix MTA basically just capture ‘From’ and ‘To’ field while the subject is not logged to the maillog. There are simple steps to enable logging of the e – mail subject in postfix maillog. This will very useful for email administrators when performing troubleshooting of problems related with email.

1. Assume that postfix has been installed. Open the postfix main configuration file :
# vi /etc/postfix/main.cf
2. Uncomment the following :
..
..
header_checks = regexp:/etc/postfix/header_checks
..
..
3. Open /etc/postfix/header_checks file and add the following line at the bottom :
# vi /etc/postfix/header_checks
..
..
/^Subject:/     WARN
4. Run postmap to apply the new configuration in /etc/postfix/header_checks :
# postmap /etc/postfix/header_checks :
5. Restart or reload postfix configuration :
# service postfix restart

or

# postfix reload
6. Test send email with subject:test-ABC :
# telnet localhost 25
Trying ::1...
Connected to localhost.
Escape character is '^]'.
220 centos66.ehowstuff.local ESMTP Postfix
ehlo abc.com
250-centos66.ehowstuff.local
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
mail from:admin@ehowstuff.com
250 2.1.0 Ok
rcpt to:admin@ehowstuff.com
250 2.1.5 Ok
data
354 End data with .
subject:test-ABC
.
250 2.0.0 Ok: queued as 196AD1FDEA
quit
221 2.0.0 Bye
Connection closed by foreign host.
7. Please confirm that the subject “test – ABC” is appearing in the log :
# tail -f /var/log/maillog
Apr  6 23:41:28 centos66 postfix/smtpd[4919]: connect from localhost[::1]
Apr  6 23:41:58 centos66 postfix/smtpd[4919]: 196AD1FDEA: client=localhost[::1]
Apr  6 23:42:07 centos66 postfix/cleanup[4924]: 196AD1FDEA: warning: header subject:test-ABC from localhost[::1]; from= to= proto=ESMTP helo=
Apr  6 23:42:07 centos66 postfix/cleanup[4924]: 196AD1FDEA: message-id=<20150406154158.196AD1FDEA@centos66.ehowstuff.local>
Apr  6 23:42:07 centos66 postfix/qmgr[4914]: 196AD1FDEA: from=, size=365, nrcpt=1 (queue active)
Apr  6 23:42:09 centos66 postfix/smtpd[4919]: disconnect from localhost[::1]

Postfix_logo

How to Reset the Directory Manager Password on RHEL 7 / CentOS 7
How to Reset the Directory Manager Password on RHEL 7 / CentOS 7

It is best practice to remember passwords, but because too many passwords, sometimes we forget. We are not encouraged to write the password on any paper or share the password...

How to Find Big Files Size on Linux RHEL/CentOS
How to Find Big Files Size on Linux RHEL/CentOS

As the linux administrator, sometimes we have to identify which files are most take much space in the linux server resulting in low free space. Low disk space can also...

Why Linux users should worry about malware and what they can do about it
Why Linux users should worry about malware and what they can do about it

Don’t drop your guard just because you’re running Linux. Preventing the spread of malware and/or dealing with the consequences of infection are a fact of life when using computers. If...

How to Reset Forgotten Root Password on Linux RHEL 7 / CentOS 7
How to Reset Forgotten Root Password on Linux RHEL 7 / CentOS 7

This short howto will explain the steps to reset a lost root password or to reset a forgotten root password on Linux RHEL 7 or CentOS 7. Basically, we will...

How to Update CentOS or Upgrade CentOS to the Latest Version
How to Update CentOS or Upgrade CentOS to the Latest Version

Recently, the latest version of CentOS 7.3 was released. All users of CentOS 7.0, 7.1 and 7.2 can upgrade their system to the most recent. This quick guide will explain...

How to Change your WordPress Username, Nickname and Display Name in MySQL
How to Change your WordPress Username, Nickname and Display Name in MySQL

After you create an account log in WordPress, you may want to change your WordPress username, as appropriate or due to security reason. However, you can not do this from...

How to Enable SSH Root Login on Ubuntu 16.04
How to Enable SSH Root Login on Ubuntu 16.04

As what we wrote in the previous article on how to allow SSH root on Ubuntu 14.04, after installing a fresh new copy of Ubuntu 16.04 LTS, we find that...

How to Change UUID of Linux Partition on CentOS 7
How to Change UUID of Linux Partition on CentOS 7

UUID (Universally Unique IDentifier) should be unique and it is used to identify storage devices on a linux system. If you cloned a virtual machine from vCenter, the metadata containing...

Leave a Reply

Your email address will not be published. Required fields are marked *