Postfix + Dovecot Mail Server Setup on Oracle Cloud

1. Prerequisites

Oracle Cloud Free Tier account with a Linux instance (Ubuntu/Oracle Linux)
Domain name (e.g., yourdomain.com)
Root/Sudo access to the server

2. Install Required Packages

sudo apt update && sudo apt upgrade -y
sudo apt install postfix dovecot-core dovecot-imapd mailutils -y

3. Configure Postfix

Edit the main configuration file:

sudo nano /etc/postfix/main.cf

Add or update these settings:

myhostname = mail.yourdomain.com
mydomain = yourdomain.com
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
inet_interfaces = all
home_mailbox = Maildir/

Restart Postfix:

sudo systemctl restart postfix

4. Configure Dovecot

Enable IMAP and Maildir format:

sudo nano /etc/dovecot/conf.d/10-mail.conf

Ensure this setting is present:

mail_location = maildir:~/Maildir

Restart Dovecot:

sudo systemctl restart dovecot

5. Set Up SSL/TLS with Let's Encrypt

Install Certbot and get a certificate:

sudo apt install certbot -y
sudo certbot certonly --standalone -d mail.yourdomain.com

Configure SSL for Postfix:

sudo nano /etc/postfix/main.cf

Add:

smtpd_tls_cert_file=/etc/letsencrypt/live/mail.yourdomain.com/fullchain.pem
smtpd_tls_key_file=/etc/letsencrypt/live/mail.yourdomain.com/privkey.pem

Configure SSL for Dovecot:

sudo nano /etc/dovecot/conf.d/10-ssl.conf

Add:

ssl = required
ssl_cert =



            Restart services:
            sudo systemctl restart postfix dovecot



        
            6. Automate SSL Renewal
            Add a cron job to renew SSL automatically:
            sudo crontab -e
            Insert this line:
            0 0 * * * certbot renew --quiet && systemctl reload postfix dovecot
        
		
            7. Set Up SMTP Relay (Optional, if Port 25 is Blocked)
            Configure Postfix to use Gmail or another relay:
            sudo nano /etc/postfix/main.cf
            Add:
             relayhost = [smtp.gmail.com]:587
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd

            Create credentials:
            sudo nano /etc/postfix/sasl_passwd
            Add:
            [smtp.gmail.com]:587 your-email@gmail.com:your-password
            Apply changes:
            sudo postmap /etc/postfix/sasl_passwd
sudo systemctl restart postfix
        

        
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