How to Install and Configure Dovecot on Linux OS?

Dovecot is an open-source IMAP and POP3 Mail Server for Linux and UNIX Operating Systems, which is used to receive incoming emails on a server from Postfix.

We believe you have Postfix preinstalled. The steps to install Dovecot on all Linux OS are listed below.

Install Dovecot

CentOS / AlmaLinux / Rocky Linux
# sudo yum install dovecot -y 

Ubuntu / Debian:
# sudo apt update
# sudo apt install dovecot-core dovecot-imapd dovecot-pop3d -y

Configure Dovecot Base Settings

Edit the main config file:

# sudo vi /etc/dovecot/dovecot.conf

Add or modify the following lines:

protocols = imap pop3
mail_location = maildir:~/Maildir

Configure Authentication

# sudo vi /etc/dovecot/conf.d/10-auth.conf

Uncomment or add:

auth_mechanisms = plain login

Set Mail Directory Format

# sudo vi /etc/dovecot/conf.d/10-mail.conf

Add or update this line:

mail_location = maildir:~/Maildir

Configure Postfix SMTP Authentication via Dovecot

# sudo vi /etc/dovecot/conf.d/10-master.conf

Uncomment and modify this section:

service auth {
    unix_listener /var/spool/postfix/private/auth {
        mode = 0666
        user = postfix
        group = postfix
    }
} 

Configure POP3 Settings (Optional)

# sudo vi /etc/dovecot/conf.d/20-pop3.conf

Uncomment or add:

pop3_uidl_format = %08Xu%08Xv
pop3_client_workarounds = outlook-no-nuls oe-ns-eoh

Create a Test Mail User

# sudo useradd test
# sudo passwd test

Create Mail Directory

# sudo mkdir /home/test/Maildir
# sudo chown test:test /home/test/Maildir
# sudo chmod -R 700 /home/test/Maildir

Start Dovecot Service

# sudo systemctl start dovecot
# sudo systemctl enable dovecot

Configure Postfix to Use Dovecot for SMTP Authentication

# sudo vi /etc/postfix/main.cf

Add or modify the following:

Authentication
smtpd_sasl_auth_enable = yes
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
smtpd_sasl_security_options = noanonymous
smtpd_sasl_local_domain = $hostname
broken_sasl_auth_clients = yes

Restart Postfix

# sudo systemctl restart postfix

Open Required Ports in the Firewall

Open necessary ports for email services
# sudo iptables -I INPUT -p tcp -m multiport --dports 110,143,465,587,993,995 -j ACCEPT

Save firewall rules (varies by distro)
CentOS / RHEL:
# sudo service iptables save

For firewalld (CentOS 7+):
# sudo firewall-cmd --permanent --add-port=110/tcp
# sudo firewall-cmd --permanent --add-port=143/tcp
# sudo firewall-cmd --permanent --add-port=465/tcp
# sudo firewall-cmd --permanent --add-port=587/tcp
# sudo firewall-cmd --permanent --add-port=993/tcp
# sudo firewall-cmd --permanent --add-port=995/tcp
# sudo firewall-cmd --reload

For Ubuntu/Debian UFW:
# sudo ufw allow 110,143,465,587,993,995/tcp

You now have a fully working Postfix + Dovecot email system with SMTP, IMAP, and POP3 support on your Linux server.