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Based on the valuable documents at: server-world.info
SMTP: Postfix
IMAP: Dovecot
No virtual domains, only Linux users will have email accounts
Tried to be as simple as possible
Hostname: mail.386387.xyz
Mail Domain: 386387.xyz
Operating System: Debian 12/11 or Ubuntu 24.04/22.04 LTS Server
My User Name: exforge
An MX record must be created at the DNS Server with the value of mail.386387.xyz
sudo apt update
sudo apt -y install postfix sasl2-bin
Select No configuration at the install question, we will configure it manually.
sudo cp /usr/share/postfix/main.cf.dist /etc/postfix/main.cf
sudo nano /etc/postfix/main.cf
around line 78-82: uncomment
mail_owner = postfix
around line 94-98: uncomment and change hostname
myhostname = mail.386387.xyz
around line 102-106: uncomment and change domainname
mydomain = 386387.xyz
around line 123-127: uncomment
myorigin = $mydomain
around line 137-141: uncomment
inet_interfaces = all
around line 185-189: uncomment
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
around line 228-232: uncomment
local_recipient_maps = unix:passwd.byname $alias_maps
around line 270-277: uncomment
mynetworks_style = subnet
around line 287-294: add your local network
mynetworks = 127.0.0.0/8, 10.0.0.0/24
around line 407-416: uncomment
alias_maps = hash:/etc/aliases
around line 418-427: uncomment
alias_database = hash:/etc/aliases
around line 440-449: uncomment
home_mailbox = Maildir/
around line 576-585: change the line as below
(remove $mail_name (Ubuntu) (Debian/GNU) for Debian)
From:
#smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
To:
smtpd_banner = $myhostname ESMTP
around line 650 - 659: add/change
sendmail_path = /usr/sbin/postfix
around line 655 - 664: add/change
newaliases_path = /usr/bin/newaliases
around line 660 - 669: add/change
mailq_path = /usr/bin/mailq
around line 666 - 675: add/change
setgid_group = postdrop
around line 670 - 679: comment out
#html_directory =
around line 674 - 683: comment out
#manpage_directory =
around line 679 - 688: comment out
#sample_directory =
around line 683 - 692: comment out
#readme_directory =
add to the end:
# limit email size to 10MB
message_size_limit = 10485760
# limit mailbox size to 1GB
mailbox_size_limit = 1073741824
# SMTP-Auth setting
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
smtpd_sasl_auth_enable = yes
smtpd_sasl_security_options = noanonymous
smtpd_sasl_local_domain = $myhostname
smtpd_recipient_restrictions = permit_mynetworks, permit_auth_destination, permit_sasl_authenticated, reject
sudo newaliases
sudo systemctl restart postfix
sudo apt -y install dovecot-core dovecot-pop3d dovecot-imapd
sudo nano /etc/dovecot/dovecot.conf
around line 30: uncomment
listen = *, ::
sudo nano /etc/dovecot/conf.d/10-auth.conf
around line 10: uncomment and change ( allow plain text auth )
disable_plaintext_auth = no
around line 100: add/change
auth_mechanisms = plain login
sudo nano /etc/dovecot/conf.d/10-mail.conf
around line 30: change to Maildir
mail_location = maildir:~/Maildir
sudo nano /etc/dovecot/conf.d/10-master.conf
around line 107: uncomment and add
# Postfix smtp-auth
unix_listener /var/spool/postfix/private/auth {
mode = 0666
user = postfix
group = postfix
}
sudo systemctl restart dovecot
Break Time
At this point we have a very basic mail config, all our linux users at mail.386387.xyz have mail addresses. They can access smtp at port 25 and imap at port 143. But unfortunately there is no encryption.
At the next step we will add SSL encrytpion and that will change our smtp port to 587.
We will use Certbot tool of Let's Encrypt to have a free certificate
sudo apt -y install certbot
Enter an email address and accept # TOS.
sudo certbot certonly --standalone -d mail.386387.xyz
Certificates are installed to /etc/letsencrypt/live/mail.386387.xyz/
sudo nano /etc/postfix/main.cf
Add to the end
smtpd_use_tls = yes
smtp_tls_mandatory_protocols = !SSLv2, !SSLv3
smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3
smtpd_tls_cert_file = /etc/letsencrypt/live/mail.386387.xyz/fullchain.pem
smtpd_tls_key_file = /etc/letsencrypt/live/mail.386387.xyz/privkey.pem
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
sudo nano /etc/postfix/master.cf
Around line 17 - 19 uncomment like below
submission inet n - y - - smtpd
-o syslog_name=postfix/submission
# -o smtpd_tls_security_level=encrypt
-o smtpd_sasl_auth_enable=yes
-o smtpd_tls_auth_only=yes
For Ubuntu 22.04 and Debian 11
Around line 29-33: uncomment like below
smtps inet n - y - - smtpd
-o syslog_name=postfix/smtps
-o smtpd_tls_wrappermode=yes
For Ubuntu 24.04 and Debian 12 Around line 36: insert below lines
smtps inet n - y - - smtpd
-o syslog_name=postfix/smtps
-o smtpd_tls_wrappermode=yes
sudo nano /etc/dovecot/conf.d/10-ssl.conf
Around line 12: Specify certificates (change as below)
Remember to change domain names to yours:
ssl_cert = </etc/letsencrypt/live/mail.386387.xyz/fullchain.pem
ssl_key = </etc/letsencrypt/live/mail.386387.xyz/privkey.pem
sudo systemctl restart postfix dovecot
For Linux User exforge at mail.386387.xyz
Thunderbird Config:
All Linux users already have mail accounts with their login names and passwords.
To add a new mail user, you need to add a user to your server
sudo useradd -d /home/exforge -m exforge
And you need to give her a password too
sudo passwd exforge
If you want to use aliases, say postmaster and abuse for user exforge.
First create Linux users
sudo useradd -d /home/postmaster -m postmaster
sudo useradd -d /home/abuse -m abuse
sudo passwd postmaster
sudo passwd abuse
Add them to /etc/aliases file
sudo nano /etc/aliases
Fill as below:
# See man 5 aliases for format
postmaster: exforge
abuse: exforge
Activate aliases
sudo newaliases
sudo systemctl restart postfix dovecot