How to Setup a Complete Mail Server (Postfix) using ‘SquirrelMail’ (Webmail) on Ubuntu/Debian

Creating a mail server on Linux powered machines can be one of the most essential things that every system administrator needs to do while configuring his servers for the first time, if you don’t know what it means; it’s simple, if you have a website like “example.com”, you can create an email account like “[email protected]” to use it to send / receive emails easily instead of using services like Hotmail, Gmail, Yahoo Mail, etc.

Setup Postfix Mail Server in Debian

Setup Postfix Mail Server in Ubuntu/Debian

In this article, we’ll learn how to do so by installing the Postfix with “SquirrelMail” webmail application and its dependencies on Debian/Ubuntu machines.

Step 1: Installing Apache2 and PHP7

1. In order to create a running mail server using “SquirrelMail”, we’ll have to install both Apache2 & PHP7 packages first, to do so, run.

$ sudo apt-get update -y
$ sudo apt-get upgrade -y
$ sudo apt-get install apache2 php7
Install Apache and PHP

Install Apache and PHP

Step 2: Installing Postfix Mail Server

2. Postfix is a mail transfer agent (MTA) which is the responsible software for delivering & receiving emails, it’s essential in order to create a complete mail server.

To install it on Ubuntu/Debian or even Mint, run:

$ sudo apt-get install postfix

During installation, you will be asked to choose the type of mail configuration, choose “Internet Site”.

Install Postfix in Ubuntu

Install Postfix in Ubuntu

3. Now enter the fully qualified domain name that you want to use for send and receive mails.

Set Postfix Mail Domain

Set Postfix Mail Domain

4. Once the FQDN set, you’ve restart the Postfix mail server using.

$ sudo service postfix restart
Start Postfix Mail Server in Ubuntu

Start Postfix Mail Server in Ubuntu

Step 3: Installing Dovecot

5. Dovecot is a mail delivery agent (MDA), it delivers the emails from/to the mail server, to install it, run the following command.

$ sudo apt-get install dovecot-imapd dovecot-pop3d
Install Dovecot in Ubuntu

Install Dovecot in Ubuntu

6. Next, restart Dovecot service using the following command.

$ sudo service dovecot restart
Start Dovecot in Ubuntu

Start Dovecot in Ubuntu

Step 4: Installing SquirrelMail in Ubuntu

7. SquirrelMail is the email server that you’ll be using to manage emails on your server, it has a simple web interface to do the job, it can be customized by installing more modules & themes.

$ wget https://sourceforge.net/projects/squirrelmail/files/stable/1.4.22/squirrelmail-webmail-1.4.22.zip
$ unzip squirrelmail-webmail-1.4.22.zip
$ sudo mv squirrelmail-webmail-1.4.22 /var/www/html/
$ sudo chown -R www-data:www-data /var/www/html/squirrelmail-webmail-1.4.22/
$ sudo chmod 755 -R /var/www/html/squirrelmail-webmail-1.4.22/
$ sudo mv /var/www/html/squirrelmail-webmail-1.4.22/ /var/www/html/squirrelmail

8. After the installation, you will have to run this command in order to configure SquirrelMail.

$ sudo perl /var/www/html/squirrelmail/config/conf.pl
Configure Squirrelmail in Ubuntu

Configure Squirrelmail in Ubuntu

09. Next, enter “2” in order to edit the server settings, and you will be prompted to it.

Squirrelmail Server Settings

Squirrelmail Server Settings

10. Now enter “1” in order to change the domain name and write up your domain (e.g: tecmint.com).

Set Mail Domain

Set Mail Domain

11. Go back to the main menu by writing “R” and hitting the enter key, write “4” in order to configure the general options.

You see “Allow server-side sorting”? Enter “11” and change it from “false” to “true” by entering “y”. Now hit the Enter key, and enter the “S” key in order to save the configuration file.

Configure General Mail Options

Configure General Mail Options

12. You can now access the mail server by going to domain.com/squirrelmail.

Access Squirrelmail in Ubuntu

Access Squirrelmail

Step 5: Creating Mail Users

13. In order to start using squirrelmail webmail, you’ll have to create a new user, to do so, run.

$ sudo useradd myusername

Replace “myusername” with the user name you want, create a password for the new user by running.

$ sudo passwd myusername

14. Create a home folder for the user in /var/www/html/myusername and make it default home directory.

$ sudo mkdir -p /var/www/html/myusername
$ usermod -m -d /var/www/html/myusername myusername

15. Now go back to the login page and enter the user name and the password of newly created user.

Access Squirrelmail in Ubuntu

Access Squirrelmail

You will be surprise to see the following error message.

Login to Squirrelmail

Login to Squirrelmail

This is just a problem in the permissions, you have to give the user “myusername” the complete permissions on its home folder.

$ sudo chown -R myusername:myusername /var/www/html/myusername

16. Once permission set, you should able to login into squirrelmail.

Squirrelmail Mail Interface

Squirrelmail Mail Interface

You can try to send email from it, or you can try to receive emails by sending it to “[email protected]” , don’t forget to replace “myusername” with the user name you created.

If you faced any other error.. Just check the “/var/log/mail.err” file, all the error message will be stored there, you won’t lose your way :)

Have you tried to create an email server before? How did it go? Have you used SquirrelMail or any other mail server before? What do you think about it?

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Aaron Kili

Aaron Kili is a Linux and F.O.S.S enthusiast, an upcoming Linux SysAdmin, web developer, and currently a content creator for TecMint who loves working with computers and strongly believes in sharing knowledge.

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223 Responses

  1. Hameed Hussain says:

    Error opening ../data/default_pref
    Could not create an initial preference file!
    /var/local/squirrelmail/data/ should be writable by user www-data
    Please contact your system administrator and report this error.

  2. Deepak says:

    Hi there,

    I read this article and follow all the instructions to set up the Squirrelmail and worked too.

    When I login with myusername and password, it gives this error

    ERROR
    Error opening ../data/default_pref
    Could not create an initial preference file!
    /var/local/squirrelmail/data/ should be writable by user www-data
    Please contact your system administrator and report this error.

    This is the permission of folders http://prntscr.com/qktqcb.

    And second thing via command line using this command usermod -m -d /var/www/etraininghq/etraining etraining.

    usermod: no changes

    Please help me if you have any solution.

    Thanks in advance

  3. Sameh Ali says:

    SquirrelMail version 1.4.22
    By the SquirrelMail Project Team
    ERROR
    An unknown user or password is incorrect.
    Go to the login page

  4. Vijay Kumar Kanta says:

    I feel like a total noob which I am, but even after assigning perms to myusername:myusername the login just wouldn’t succeed. It still gives me the Query: CAPABILITY error, and then in the logs, it says mkdir() failed due to insufficient permissions.

  5. Anton W says:

    Hi, is it possible to login in thunderbird with this mail server?

  6. Abraham Moreno says:

    Simple question. can I build this on the same server I use to host my website? or does it have to be an independent server?

  7. Matthew Delahoussaye says:

    Hi, This is a great guide, and I am a complete novice to all this. I have come across an issue and cannot figure out how to solve it.

    When setting up, I got a screen asking about SSL as I have SSL setup on my server and a forced redirect to HTTPS. It asked me for a name, so I put in my hostname mattemedia.co.uk, and followed the rest of the guide.

    Now when I go to open SquirrelMail login, I get a 404 – not available on port 443…

  8. J.Jose says:

    Try the command sudo a2enmod php7.0.

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