Exim is a mail transfer agent (MTA), which is mostly used on UNIX operating systems though it has been recently ported to other operating systems. Exim is open sourced and one of the most widely used mail-servers (about 56% globally). For using the exim mail server, there is no Mailman configuration needed, you can use the standard options.

The Exim mail server management uses SMTP (Simple Mail Transfer Protocol), the standard protocol for sending e-mails. It employs the IMAP (Internet Mail Access Protocol) and the POP3 (Post Office Protocol) to receive the electronic mail.

When an email is sent, it is transferred to an SMTP server through the internet. This server forwards the email to the corresponding recipient using the Exim application.


Exim is easily configurable and is known to be highly secured as compared to other MTAs. It consists of an access controlled list based system and the administrator has the facility to control and limit the users of the system. Exim also allows for the easy integration of anti-virus and anti-spam applications which makes it suitable to send highly sensitive data as well.

Sections of Operation

Exim consists of the following modes of operation –

  • ACL (Access Control List): It controls who can send emails.
  • Router Section: It includes elements that process the addresses of emails at the time of delivery.
  • Transport Section: Transports message content from the source to the destination.
  • Retry Section: Retries sending messages after the first delivery has failed.
  • Rewrite Section: Defines how addresses of incoming emails should be re-written.
  • Authentication Section: Authenticates client login.

How to Setup an Exim Mail Server

Configuring an Exim mail server management system is easier in a UNIX like operating system. You can install such an operating system on your computer provided you have sufficient disk space. This is a guide for setting up Exim on Ubuntu 12.04.


  • Configured droplet’s hostname.
  • Already set up FQDN (Fully Qualified Domain Name).
  • Created DNS records.
  • Created SPF record.


  1. Software Update

Update your existing software by executing –

sudo apt-get update && sudo apt-get -y upgrade && sudo apt-get -y dist-upgrade && sudo apt-get -y autoremove

  1. Installation

To install Exim, execute –

sudo apt-get -y install exim4

To configure Exim, execute –

sudo dpkg-reconfigure exim4-config

You can re-configure your system by running the wizard again.

  1. Mail Server Configuration Type

While running the wizard, you will encounter a window which will ask for the server configuration. Select –

internet site; mail is sent and received using SMTP

  1. Enter FQDN

Enter your system’s FQDN using –


  1. SMTP Listener

The configuration wizard will ask you to enter the interface that your Exim system will listen to. Enter – 6.     

     6. Mail Destinations When prompted to enter your mail destinations from which your Exim will accept email, enter –·         FQDN·         Local hostname·         localhost.localdomain;·         localhost

   7.      DNS Queries Select ‘No’ when you are prompted to keep DNS queries minimalistic.

   8.      Delivery Method Choose whichever delivery method format you would like.

   9.      Configuration File Choose un-split configuration by highlighting ‘No’ and press enter.

  10.  Postmaster Address In the final command prompt, you will be asked for your specific postmaster recipients. Enter the following command –  root [email protected] Make sure you have substituted your values in place of ‘you’, ‘yourdomain’, and ‘tld’.

  11.  Test Your Configuration Finally, test your configuration with a valid address.

For any more information on the latest versions of Exim or the installation procedure, check out their website – exim.org.

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One thought on “What Is an Exim Mail Server? What Are the Ins and Outs of Exim Mail Server?”

  1. John Mathew says:

    Great article on what is exim mail server, and what are ins and outs of it. Exim is also widely used with the GNU Mailman mailing list manager, and cPanel. Great Work Keep it up.

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