Learn how to set up a email server on a Cloud Server running CentOS 7. This tutorial features Postfix as an SMTP server, Dovecot for POP/IMAP functionality, and RoundCube as a webmail program for users to check and receive email from a web browser.
The tutorial will also walk you through the process of creating and using a self-signed SSL certificate for use in securing incoming and outgoing email connections.
Set up your own professional email server in the blink of an eye. You benefit from large and expandable storage space, your own domain, automatic encryption as well as calendar and office functions or email archiving. IONOS also offers the highest security standards in ISO-certified data centers.
To check the status of Postfix on the server, use the command:
sudo postfix statusIf Postfix is installed and running, you will see the output:
[user@localhost ~]# sudo postfix status
postfix/postfix-script: the Postfix mail system is running: PID: 1681If you have a firewall, you will need to allow access to the following ports:
We will create a self-signed SSL certificate to secure incoming and outgoing email connections:
sudo openssl req -x509 -nodes -newkey rsa:2048 -keyout mailserver.key -out mailserver.crt -nodes -days 365Answer the questions at the prompts, or just hit [Enter] to leave an answer blank. This command will create two files: mailserver.key and mailserver.crt.
Create a folder for the SSL certificate files:
sudo mkdir /etc/postfix/sslThen move the files into this folder:
sudo mv mailserver.key /etc/postfix/ssl
sudo mv mailserver.crt /etc/postfix/sslSSL certificates from IONOS
Protect your domain and gain visitors' trust with an SSL-encrypted website!
Easy to activateProven safety24/7 assistanceThe following steps will enable a basic Postfix set-up, allowing you to send and receive mail. For more information on these configurations, consult the official documentation.
Before you begin the configuration changes, be sure that you have the most recent version of Postfix by running the command:
sudo yum update postfixFirst we will edit the /etc/postfix/master.cf file to enable the submission daemon to send and accept mail securely:
sudo nano /etc/postfix/master.cfDelete the hash mark (#) to un-comment the following lines:
#submission inet n - n - - smtpd
# -o syslog_name=postfix/submission
# -o smtpd_tls_security_level=encrypt
# -o smtpd_sasl_auth_enable=yes
# -o smtpd_recipient_restrictions=permit_sasl_authenticated,reject
# -o milter_macro_daemon_name=ORIGINATINGSave and exit the file.
The /etc/postfix/main.cf file contains the configuration options for your Postfix installation. Edit this file:
sudo nano /etc/postfix/main.cfMake the following changes:
Set Hostname
Edit the line which reads:
#myhostname = host.domain.tldDelete the hash mark (#) to un-comment the line, and replace host.domain.tld with the hostname of the server:
myhostname = example.comSet Domain
Edit the line which reads:
#mydomain = domain.tldDelete the hash mark (#) to un-comment the line, and replace domain.tld with the domain you want to receive mail for:
mydomain = example.comEnable Other Settings
Delete the hash mark (#) to un-comment the following lines:
#myorigin = $myhostname
#inet_interfaces = all
#inet_interfaces = localhost
#inet_protocols = all
#mydestination = $myhostname, localhost.$mydomain, localhost
#home_mailbox = Maildir/Add Configurations
Finally, add the following lines to the end of the file:
smtpd_tls_key_file = /etc/postfix/ssl/mailserver.key
smtpd_tls_cert_file = /etc/postfix/ssl/mailserver.crt
smtpd_use_tls=yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_tls_security_level=maySave and exit the file, then restart Postfix to load the new configurations:
sudo systemctl restart postfixTo test Postfix we will telnet to the server and perform a basic "handshake protocol," just as an email program would.
First, install Telnet:
sudo yum install telnetOnce Telnet is installed, use it to connect to the server's SMTP port:
telnet localhost 25The server will respond with:
[user@localhost ~]$ telnet localhost 25
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.Start by telling the server who the mail is being sent from:
mail from: some-person@some-other-server.comThen tell the server who you are sending mail to, replacing user@example.com with your own username and domain name:
rcpt to: user@example.comNow add a simple message. Tell the server your message body starts here:
data Type the message, then follow it with [Enter], a period ., and [Enter]:
hello world
.Close the session by typing quit and hitting Enter.
If you are successful, your test message will appear in /home/username/Maildir/new. You can view this message with the command:
ll /home/username/Maildir/newTo read the message, copy and paste the name of the file (it will be a long name like 1481229255.Vfd01I402b66aM546595.example.com) and read it with more:
more 1481229255.Vfd01I402b66aM546595.example.comYou will see the email message, along with all of the header information:
From some-person@some-other-server.com Thu Dec 8 19:43:10 2016
Return-Path: <some-person@some-other-server.com>
X-Original-To: user@example.com
Delivered-To: user@example.com
Received: from localhost (localhost [127.0.0.1])
by mail.example.com (Postfix) with SMTP id 6CFD589184
for <user@example.com>; Thu, 8 Dec 2016 19:42:33 +0000 (UTC)
Message-Id: <20161208194238.6CFD589184@mail.oxnardindustries.com>
Date: Thu, 8 Dec 2016 19:42:33 +0000 (UTC)
From: some-person@some-other-server.com
hello worldWe will be using Dovecot as a POP3/IMAP server, so that users can receive and check their email. You can find more information about Dovecot on the Dovecot website.
Install Dovecot with the command:
sudo yum install dovecotYou can check on the status of Dovecot with the command:
sudo systemctl status dovecotIf Dovecot is running, you will see output similar to:
[user@mail dovecot]$ sudo systemctl status dovecot -l
● dovecot.service - Dovecot IMAP/POP3 email server
Loaded: loaded (/usr/lib/systemd/system/dovecot.service; disabled; vendor preset: disabled)
Active: active (running) since Thu 2016-12-08 21:04:48 UTC; 3s ago
Process: 8985 ExecStartPre=/usr/libexec/dovecot/prestartscript (code=exited, status=0/SUCCESS)
Main PID: 8989 (dovecot)
CGroup: /system.slice/dovecot.service
├─8989 /usr/sbin/dovecot -F
├─8992 dovecot/anvil
├─8993 dovecot/log
└─8995 dovecot/config
Dec 08 21:04:48 example.com systemd[1]: Starting Dovecot IMAP/POP3 email server...
Dec 08 21:04:48 example.com systemd[1]: Started Dovecot IMAP/POP3 email server.
Dec 08 21:04:48 example.com dovecot[8989]: master: Dovecot v2.2.10 starting up for imap (core dumps disabled)Active: active (running) since Thu 2016-12-08 21:04:48 UTC; 3s agoThis means that Dovecot is installed and running.
Roundcube is a free, open source webmail program with robust built-in multilingual capabilities, and many convenient features for your users. You can read more about Roundcube on the Roundcube website.
Roundcube requires several PHP and MariaDB packages as a prerequisite. Install and/or update these first with the command:
sudo yum install mysql mariadb-server php php-common php-json php-xml php-mbstringNext, create a MariaDB username and database for the Roundcube installation. Log into the MariaDB client with the command:
mysql -u root -p Log in with the root password, then create a Roundcube database:
create database roundcube_db;Create a user for this database. Note: Be sure to give the user a strong password.
grant all on roundcube_db.* to roundcube_user@localhost identified by 'roundcube_db_password';Replace:
Then exit MariaDB:
quit;Go to your website's document root. Download the current release from the Roundcube website by using the command:
sudo wget [download URL]To find the download URL, visit the current release page on the Roundcube website. Copy the URL for the green "Download" link. You can paste it into the command line by clicking Shift + Insert.
For example, to download the current stable release as of this article's publication the command is:
sudo wget https://github.com/roundcube/roundcubemail/releases/download/1.2.3/roundcubemail-1.2.3-complete.tar.gzUncompress this file using the command:
sudo tar -xvf [filename]You can use tab completion to make this process easier. Type sudo tar -xvf roundcube then hit Tab. The shell will automatically fill out the rest of the file name on the command line.
To unzip the file downloaded above, the command is:
sudo tar -xvf roundcubemail-1.2.3-complete.tar.gzRename the extracted directory roundcube:
sudo mv roundcubemail-1.2.3 roundcubeSet the ownership of the files to the Apache user:
sudo chown -R apache:apache roundcubeTo complete the installation, switch to a browser and go to the URL http://example.com/roundcube/installer/.
Scroll down to the bottom of the page and click NEXT.
In the next section, you will need to fill out the database information.
Fill out the MariaDB database name, username, and password which you created above. Then scroll down and click CREATE CONFIG.
Note: There are many potential configurations. You can change or set them at any time in the future.
After the config file is created, click CONTINUE to continue.
Click the Initialize database button to set up the database.
Test the mail server configuration by sending a test SMTP email.
Then click Send test mail. After a few moments, check the external email account to see if your email was sent.
Test the IMAP configurations by logging in with your username and password.
Note that your username is NOT your full email address. For example, log in with the username jdoe, not jdoe@example.com.
Now that the configuration is complete, you can log in at http://example.com/webmail to check and send email.
Professional Email Address & Personal Domain Name
Get an email address as professional and unique as you are including a free matching domain!
Address bookCalendarVirus protection
Finding a suitable operating system that meets your own requirements is usually not very difficult in the private sector. Most of the time, it’s just down to personal taste whether you favor Windows, macOS, or Linux. The search for a system solution for enterprise and server environments is far more difficult and complex. When selecting, factors such as long-term support, security, and cost play a...
Anyone familiar with the technicalities of the e-mail sending process will invariably come across the term “SMTP server” at some point. But how exactly does this unit of hardware and software – which invisibly transports the typical consumer’s e-mail from A to B – work? Understanding how this type of server functions is information that can be used to your advantage when it comes to manually...
Learn how to set up a mail server on a Cloud Server running Ubuntu 16.04. This tutorial features Postfix as an SMTP server, Dovecot for POP/IMAP functionality, and Squirrelmail as a webmail program.
Learn how to install and use Apache's `mod_wsgi` module to run Python scripts in a web page. This Apache module can be used to serve web pages written in Python, or to render web pages with embedded Python scripts.
PhpMyAdmin is a convenient way to manage MySQL/MariaDB for those who prefer a browser-based interface over the traditional command-line interface. Learn how to install and use phpMyAdmin on a Cloud Server with Linux (CentOS 7).
Provide powerful and reliable service to your clients with a web hosting package from IONOS.
View packages