Mail Servers

    How to Install Postfix on CentOS/RHEL 7/6/5

    RahulBy Updated:15 Comments2 Mins Read

    Postfix is fast and popular SMTP server widely used. The main job of postfix is to relay mail locally or to the intended destination outside the network. Some of the most popular SMTP servers are Sendmail, Postfix, and Qmail. By default, Sendmail comes pre-installed with CentOS/RHEL 5. We will need to remove it and install Postfix.

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    Step 1 – Install Postfix

    If Postfix not already installed on your machine, Install it using the following command. Also, remove sendmail if already installed.

    yum remove sendmail
yum install postfix

    Make postfix as default MTA for your system using the following command

    alternatives --set mta /usr/sbin/postfix

    If above command not work and you get the output as “/usr/sbin/postfix has not been configured as an alternative for mta“. Use below command to do the same else skip it

    alternatives --set mta /usr/sbin/sendmail.postfix

    Step 2 – Configure Postfix

    Let’s start postfix configuration. Edit Postfix configuration file /etc/postfix/main.cf in your favorite editor and make following changes.

      myhostname = mail.tecadmin.net
  mydomain = tecadmin.net
  myorigin = $mydomain
  inet_interfaces = all
  mydestination = $myhostname, localhost, $mydomain
  mynetworks = 127.0.0.0/8, /32
  relay_domains = $mydestination
  home_mailbox = Maildir/

    After executing above command edit the postfix configuration file and make sure all changes are done properly.

    Step 3 – Restart Postfix Service

    As we have done basic Postfix configuration, So restart Postfix service to read changes of configuration. Also, configure to autostart on system boot.

    service postfix restart
chkconfig postfix on

    Step 4 – Open Firewall Port

    Now if your system is configured to use iptables firewall, So add firewall rules to make postfix accessible from outside, using following commands.

    iptables -A INPUT -m state --state NEW -m tcp -p tcp --dport 25 -j ACCEPT
iptables -A INPUT -m state --state NEW -m udp -p udp --dport 25 -j ACCEPT

    Thanks for using this article.

    Share.

    I, Rahul Kumar am the founder and chief editor of TecAdmin.net. I am a Red Hat Certified Engineer (RHCE) and working as an IT professional since 2009..

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    15 Comments

    1. Pratik on

      Hi,

      I am not sure how many of the readers were successfully able to get the Postfix started sending emails…

      I followed all the steps of the article. When I try sending test mail, I get following error in the /var/log/maillog

      Jul 15 12:08:46 mumsrv-qe postfix/pickup[28935]: CD221181C6E: uid=0 from=
      Jul 15 12:08:46 mumsrv-qe postfix/cleanup[30412]: CD221181C6E: message-id=
      Jul 15 12:08:46 mumsrv-qe postfix/qmgr[28936]: CD221181C6E: from=, size=479, nrcpt=1 (queue active)

      Jul 15 12:09:28 mumsrv-qe postfix/smtp[30414]: CD221181C6E: to=, relay=mobileum.com[217.78.11.57]:25, delay=42, delays=0.11/0.01/21/21, dsn=5.0.0, status=bounced (host mobileum.com[217.78.11.57] said: 550-Please turn on SMTP Authentication in your mail client. 550-(mumsrv-qe.mobileum.com) [114.143.191.38]:43898 is not permitted to relay 550 through this server without authentication. (in reply to RCPT TO command))
      Jul 15 12:09:28 mumsrv-qe postfix/cleanup[30412]: 6DAE3181C88: message-id=
      Jul 15 12:09:28 mumsrv-qe postfix/bounce[30494]: CD221181C6E: sender non-delivery notification: 6DAE3181C88
      Jul 15 12:09:28 mumsrv-qe postfix/qmgr[28936]: 6DAE3181C88: from=, size=2718, nrcpt=1 (queue active)
      Jul 15 12:09:28 mumsrv-qe postfix/qmgr[28936]: CD221181C6E: removed

      I am not sure what is missing!
      Someone please help

      Reply
      • Daniel on

        If you’re still having issues setting up Postfix please send me an email at [email protected] This article is very vague and completely not helpful to beginners. Personnaly i would suggest to use PostgreSQL as a Database backend over MySQL. feel free to email me if you or anyone else is having trouble setting up an email server

        Reply
      • Shazeb ICT on

        The above information is very helpful. Thanks, Pratik
        We know computer issues can happen at any time. That’s why we provide a 24-hour emergency IT support service. If you need us to resolve a frustrating IT issue after hours just call us and you will be working again in no time.

        Reply
    3. Jason on

      In Redhat 8 at least (and probably every other version/flavor), specifying a Subnet like l27.0.0.0/8, 32 will conflict with the earlier inet_interfaces=all statement. Can’t have both. Best to recomment the subnet line.

      Also, this article is woefully short and inadequate. You should thoroughly configure and test Postfix before making it your MTA. If you’re gonna go to the trouble of writing a config article, do it right ffs

      Reply
    4. Blazho Dzurovski on

      Really great site I Must say something I applied regarding Outbound Telemarketing Cold Calling script for answering.

      Reply
    6. preeti on

      rcpt to:
      550 5.1.1 : Recipient address rejected: User unknown in local recipient table
      i receive above error please help to find out

      Reply
    8. Murad Hosen on

      not sent outgoing mail ( gmail or hotmail.com )

      local mail are sent but not outgoing

      what can i do i am using centos 6.5 32 bit

      Reply
    11. Jones sabo on

      Excellent goods from you, man. I’ve understand your stuff previous to and you’re just extremely magnificent.

      Reply

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