Step by Step setting up a Mail Server Debian-9.0: Postfix, Dovecot, MySQL and PostfixAdmin

Mail Server: - 

Building a Mail Server on Linux Machine using different packages that separately handle SMTP, POP and IMAP. Where you can manage entire things including package installation configuration etc. 

Our Goal: -

• Postfix: sends and receives mail via the SMTP protocol. It will only relay mail on to other mail servers if the email is sent by an authenticated user, but anyone can send mail to this server for local delivery.
• Dovecot: A POP and IMAP server that manages local mail directories and allows users to log in and download their mail. It also handles user authentication.
• Postgrey: Greylists incoming mail, requiring unfamiliar deliverers to wait for a while and then resend. This is one of the better tools for cutting down on spam.
• Amavisd-new: a manager for organising various antivirus and spam checking content filters
• Clam Antivirus: A better tool to Scan Emails
• SpamAssassin: for sniffing out spam in emails.
• Postfix Admin: A good web interface to manage Domain, Mailbox, Alias etc.
• RoundCube: A web mail client tool. 

Install and Configure E-mail server:

Step 1: -  DNS Change

You have to set up your DNS with an A record that points to your mail server IP and an MX record that points to the mail servers hostname.

A           tony.in                192.168.102.10
MX          mail.tony.in           192.168.102.10

Step 2: -  Setup Hostname

We need to setup hostname 

hostname mail.tony.in

Now set the contents of /etc/hostname to be the hostname:

echo "mail.tony.in" /etc/hostname

And add your hostname to the first line of /etc/hosts:

127.0.0.1    mail.tony.in    mail

Step 3: - Install LAMP Web Server:

We need LAMP server to handle PostfixAdmin web interface and to manage RoundCube web based email client.

3A- Install Apache:-

root@mail:/home/amar# apt install apache2

3B- Install MySQL:

root@mail:/home/amar# apt install mysql-client mysql-server php-mysql

After installing  Mysql let's perform post installation task, run mysql_secure_installlation command to setup initial setting.

root@mail:/home/amar# mysql_secure_installation

Press enter button when ask for current password and follow the instruction for other changes you may require.

3C- Install PHP:

root@mail:/home/amar# apt install php7.0 php7.0-mcrypt php7.0-curl php7.0-gd php7.0-mbstring php-apcu libapache2-mod-php7.0

Step 4: - Allow required Port through Firewall

We need to allow following ports in the firewall to communicate our server with the world.

• 80 (HTTP) 
• 25 (SMTP) 
• 110 (POP3) 
• 143 (IMAP) 
• 465 (SMTPS) 
• 993 (IMAPS) 
• 995 (POPS)

Step 5: - Install Mail server

Please run the command below to install postfix and enter hostname mail.tony.in during installation process when asked.

5A- Postfix Install

root@mail:/home/amar# apt install postfix postfix-mysql  

5B- DoveCot Install

root@mail:/home/amar# apt install dovecot-core dovecot-mysql dovecot-imapd dovecot-pop3d

5C- Install all other packages including  postgrey, ClamAV  Antivirus and SpamAssassin

root@mail:/home/amar# apt install \
>   postgrey \
>   amavis \
>   clamav \
>   clamav-daemon \
>   spamassassin \
>   libdbi-perl \
>   libdbd-mysql-perl \
>   php7.0-imap \
>   postfix-policyd-spf-python

5D- Next, we need to install few optional packages that extend the abilities of the spam and virus detection, Use the command below.

root@mail:/home/amar# apt install \
>  pyzor \
>   razor \
>   arj \
>   cabextract \
>   lzop \
>   nomarch \
>   p7zip-full \
>   ripole \
>   rpm2cpio \
>   tnef \
>   unzip \
>   unrar-free \
>   zip \
>   zoo

5E- Use OpenSSL to Create a Unique Diffie-Helman Group

openssl dhparam -out /etc/ssl/private/dhparams.pem 2048
chmod 600 /etc/ssl/private/dhparams.pem

Step 6: - Configure MySQL 
A few alterations to the default MySQL configuration in /etc/mysql/mariadb.conf.d/50-server.cnf are needed. Add the following:

root@mail:/home/amar# vi /etc/mysql/mariadb.conf.d/50-server.cnf

6A- Append following line save file and restart MySQL service.

user            = mysql
pid-file        = /var/run/mysqld/mysqld.pid
socket          = /var/run/mysqld/mysqld.sock
port            = 3306
basedir         = /usr
datadir         = /var/lib/mysql
tmpdir          = /tmp
lc-messages-dir = /usr/share/mysql
sql_mode=ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION 

6B- Create a database:

Use command below to create a database and assign permission 

root@mail:/home/amar# mysql -u root -p
Enter password: *******

MariaDB [(none)]> create database mail;
Query OK, 1 row affected (0.00 sec)

MariaDB [(none)]> grant all on mail.* to 'mail'@'localhost' identified by 'mailpassword';
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> flush privileges;
Query OK, 0 rows affected (0.00 sec)
 

6C- Now Restart MySQL service

root@mail:/home/amar# systemctl restart mysql

Step 7: - Install  and Configure Postfix Admin:

Postfix Admin is installed as follows. To start things off, download the package from Sourceforge, unpack it, move it into a subdirectory of your webroot, and change ownership to the www-data user:

root@mail:/home/amar# wget http://downloads.sourceforge.net/project/postfixadmin/postfixadmin/postfixadmin-3.0.2/postfixadmin-3.0.2.tar.gz
root@mail:/home/amar# tar -xf postfixadmin-3.0.2.tar.gz
root@mail:/home/amar# rm -f postfixadmin-3.0.2.tar.gz
root@mail:/home/amar# mv postfixadmin-3.0.2 /var/www/html/postfixadmin
root@mail:/home/amar# chown -R www-data:www-data /var/www/html/postfixadmin

7A- Let's make the changes into config.inc.php

root@mail:/home/amar# vi /var/www/html/postfixadmin/config.inc.php

Make the highlighted changes in the config.inc.php

<?php
// Configuration options here override those in config.inc.php.
 
// You have to set $CONF['configured'] = true; before the
// application will run.
$CONF['configured'] = true;
  
// Database connection details.
$CONF['database_type'] = 'mysqli';
$CONF['database_host'] = 'localhost';
$CONF['database_user'] = 'mail';
$CONF['database_password'] = 'mailpassword';
$CONF['database_name'] = 'mail';

// Site Admin
// Define the Site Admin's email address below.
// This will be used to send emails from to create mailboxes and
// from Send Email / Broadcast message pages.
// Leave blank to send email from the logged-in Admin's Email address.
$CONF['admin_email'] = '';
 

Save and Exit from File
7B- Now start browser and open this URL: http://mail.tony.in/postfixadmin/setup.php
Troubleshooting: -You may get error:- Invalid query: Specified key was too long; max key length is 1000 bytes

7C- To fix above error we need to make changes into upgrade.php file
Open upgrade.php file using vi editor.

root@mail:/home/amar# vi /var/www/html/postfixadmin/upgrade.php

type syntax below and hit enter- :%s/255/100/g  it find word 500 in the file and replace it with 100

7D- After making change in the file refresh url, if things goes weill you get output as follow

7E- Now enter Setup password, what ever you need and it will give us Hash password that we need to save in config.inc.php file

You will see Hash password as in above image need to copy it and add in confi.inc.php file

7F- Open confi.inc.php and add this hash password in front of $conf['setup_password'] line as below

root@mail:/home/amar# vi /var/www/html/postfixadmin/config.inc.php

$CONF['setup_password'] = '29bef8ab87cb037af7efb8257a116469:e05ed5e6eecfa387324c4ba30f40e4d316a77685';

Save and Exit from the file.
7G- Create PostfixAdmin superAdmin login account

Super Admin account has been setup successfully.
Troubleshooting: - You may get an error "Admin is not a valid email address!Email address" during admin account setup 

This error will occur when our domain is not getting resolved, To solve it let's make and change in config.inc.php file
Open config.inc.php file  and change line as below

$CONF['emailcheck_resolve_domain']='NO'

Save and Exit from file.

Step 8: - Create Domain and add mailbox:
Let's Use created an admin user to login into postfix admin console:
User- admin@tony.in
password- created password above 

8A- Add Domain: 
Let's  add domain using steps below

8B- Add Domain: Add User mailbox
Follow the steps 1 -8 to add mailbox

One mailbox with name chinu@tony.in has been added successfully.
Step 8: - Create a User to Handle Virtual Mail Directories
We need a User account who can handle Virtual mail directories, So let's create a user using the command below:

root@mail:/home/amar# useradd -r -u 150 -g mail -d /var/vmail -s /sbin/nologin -c "Virtual maildir handler" vmail
root@mail:/home/amar# mkdir /var/vmail
root@mail:/home/amar# chmod 770 /var/vmail
root@mail:/home/amar# chown vmail:mail /var/vmail

Virtual Mail Directory "/var/vmail" using Group "mail" to allow other system's user to manage the content.

Step 9: - Configure Dovecot

Dovecot will manage all the connection for POP and IMAP, local mail directory and receive all incoming emails. Dovecot use to handle authentication for SMTP connection. We also define MySQL database connection string so Dovecot can access all the information from MySQL Database-

9A- Enable Dovecote access to MySQL database

Dovecot will access all the mailbox information including user authentication from Database, Let's make changes in the file - /etc/dovecot/dovecot-sql.conf.ext

Open dovecot-sql.conf.ext file and add database access as follow

root@mail:/home/amar# vi /etc/dovecot/dovecot-sql.conf.ext

Make the following changes as highlighted below in RED

# Database driver: mysql, pgsql, sqlite
driver = mysql

# Examples:
#   connect = host=192.168.1.1 dbname=users
#   connect = host=sql.example.com dbname=virtual user=virtual password=blarg
#   connect = /etc/dovecot/authdb.sqlite
#
connect = host=localhost dbname=mail user=mail password=mailpassword

# Default password scheme.
#
# List of supported schemes is in
# http://wiki2.dovecot.org/Authentication/PasswordSchemes
#
default_pass_scheme = MD5-CRYPT

# Define the query to obtain a user password.
#
# Note that uid 150 is the "vmail" user and gid 8 is the "mail" group.
#
password_query = \
  SELECT username as user, password, '/var/vmail/%d/%n' as userdb_home, \
  'maildir:/var/vmail/%d/%n' as userdb_mail, 150 as userdb_uid, 8 as userdb_gid \
  FROM mailbox WHERE username = '%u' AND active = '1'

# Define the query to obtain user information.
#
# Note that uid 150 is the "vmail" user and gid 8 is the "mail" group.
#
user_query = \
  SELECT '/var/vmail/%d/%n' as home, 'maildir:/var/vmail/%d/%n' as mail, \
  150 AS uid, 8 AS gid, concat('dirsize:storage=', quota) AS quota \
  FROM mailbox WHERE username = '%u' AND active = '1'

Save and Exit from File.

9B- Make changes in 10-auth.conf file

Dovecot will read the SQL configuration files, we need to enable in 10-auth.conf file lets make changes using below command.

Open 10-auth.conf file and make the changes as follow

root@mail:/home/amar# vi /etc/dovecot/conf.d/10-auth.conf

Changes are as follows:

# Disable LOGIN command and all other plaintext authentications unless
# SSL/TLS is used (LOGINDISABLED capability). Note that if the remote IP
# matches the local IP (ie. you're connecting from the same computer), the
# connection is considered secure and plaintext authentication is allowed.
disable_plaintext_auth = yes

# Space separated list of wanted authentication mechanisms:
#   plain login digest-md5 cram-md5 ntlm rpa apop anonymous gssapi otp skey
#   gss-spnego
# NOTE: See also disable_plaintext_auth setting.
auth_mechanisms = plain login

# User database specifies where mails are located and what user/group IDs
# own them. For single-UID configuration use "static" userdb.
#
# <doc/wiki/UserDatabase.txt>
 
#!include auth-deny.conf.ext
#!include auth-master.conf.ext
 
#!include auth-system.conf.ext
# Use the SQL database configuration for authentication rather than
# any of these others.
!include auth-sql.conf.ext
#!include auth-ldap.conf.ext
#!include auth-passwdfile.conf.ext
#!include auth-checkpassword.conf.ext
#!include auth-vpopmail.conf.ext
#!include auth-static.conf.ext

Save and Exit from the Files
9C- Tell Dovecot where need to store user's mail directory  Open 10-mail.conf file and make the changes as follows:

root@mail:/home/amar# vi /etc/dovecot/conf.d/10-mail.conf

Changes are as follows:

# See doc/wiki/Variables.txt for full list. Some examples:
#
#   mail_location = maildir:~/Maildir
#   mail_location = mbox:~/mail:INBOX=/var/mail/%u
#   mail_location = mbox:/var/mail/%d/%1n/%n:INDEX=/var/indexes/%d/%1n/%n
#
# <doc/wiki/MailLocation.txt>
#
mail_location = maildir:/var/vmail/%d/%n

# System user and group used to access mails. If you use multiple, userdb
# can override these by returning uid or gid fields. You can use either numbers
# or names. <doc/wiki/UserIds.txt>
mail_uid = vmail
mail_gid = mail

# Valid UID range for users, defaults to 500 and above. This is mostly
# to make sure that users can't log in as daemons or other system users.
# Note that denying root logins is hardcoded to dovecot binary and can't
# be done even if first_valid_uid is set to 0.
#
# Use the vmail user uid here.
first_valid_uid = 150
last_valid_uid = 150 

Save and Exit From the file
9D- Change Certificates file path
Open 10-ssl.conf file and make the changes as follows:

root@mail:/home/amar# vi /etc/dovecot/conf.d/10-ssl.conf

Make the changes as follows:

# SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt>
ssl = yes 

# The generated snakeoil certificate:
#ssl_cert = </etc/ssl/certs/ssl-cert-snakeoil.pem
#ssl_key = </etc/ssl/private/ssl-cert-snakeoil.key
# Purchased certificate:
ssl_cert = </etc/ssl/certs/tony.in.crt
ssl_key = </etc/ssl/private/tony.in.key

Save and Exit From the file
9E-Modify 10-master.conf 

root@mail:/home/amar# vi /etc/dovecot/conf.d/10-master.conf

 Make the changes as follows:

service auth {
  # auth_socket_path points to this userdb socket by default. It's typically
  # used by dovecot-lda, doveadm, possibly imap process, etc. Users that have
  # full permissions to this socket are able to get a list of all usernames and
  # get the results of everyone's userdb lookups.
  #
  # The default 0666 mode allows anyone to connect to the socket, but the
  # userdb lookups will succeed only if the userdb returns an "uid" field that
  # matches the caller process's UID. Also if caller's uid or gid matches the
  # socket's uid or gid the lookup succeeds. Anything else causes a failure.
  #
  # To give the caller full permissions to lookup all users, set the mode to
  # something else than 0666 and Dovecot lets the kernel enforce the
  # permissions (e.g. 0777 allows everyone full permissions).
  unix_listener auth-userdb {
    mode = 0666
    user = vmail
    group = mail
  }
 
  unix_listener /var/spool/postfix/private/auth {
    mode = 0666
    # Assuming the default Postfix user and group
    user = postfix
    group = postfix
  }

Save and Exit From the file
9F- Change postmaster setting 

root@mail:/home/amar# vi /etc/dovecot/conf.d/15-lda.conf

Changes as follows:

# Address to use when sending rejection mails.
# Default is postmaster@<your domain>.
postmaster_address = postmaster@tony.in

Save and Exit From the file
9G- Change mailbox directory permission

root@mail:/home/amar# chown -R vmail:dovecot /etc/dovecot
root@mail:/home/amar# chmod -R o-rwx /etc/dovecot

Step 10: - Configure Antivirus scan and SpamAssassin scan

Amavis, ClamAV, and SpamAssassin are the best tool to scan email, let make the changes as follow to integrate these tools.

10A-  Add Users 

root@mail:/home/amar# adduser clamav amavis
Adding user `clamav' to group `amavis' ...
Adding user clamav to group amavis
Done.
root@mail:/home/amar# adduser amavis clamav
Adding user `amavis' to group `clamav' ...
Adding user amavis to group clamav
Done.

10B- Modify configuration file

root@mail:/home/amar# vi /etc/clamav/clamd.conf

Changes as follows:

# Needed to allow things to work with Amavis, when both amavis and clamav
# users are added to one another's groups.
AllowSupplementaryGroups true

10C- Turn on Amavis

root@mail:/home/amar# vi /etc/amavis/conf.d/15-content_filter_mode

Changes as follow

use strict;
 
# You can modify this file to re-enable SPAM checking through spamassassin
# and to re-enable antivirus checking.
 
#
# Default antivirus checking mode
# Please note, that anti-virus checking is DISABLED by
# default.
# If You wish to enable it, please uncomment the following lines:
 
@bypass_virus_checks_maps = (
   \%bypass_virus_checks, \@bypass_virus_checks_acl, \$bypass_virus_checks_re);
 
#
# Default SPAM checking mode
# Please note, that anti-spam checking is DISABLED by
# default.
# If You wish to enable it, please uncomment the following lines:
 
@bypass_spam_checks_maps = (
   \%bypass_spam_checks, \@bypass_spam_checks_acl, \$bypass_spam_checks_re);
 
1;  # ensure a defined return

Save and Exit From file
10D- Enable SpamAssassin

root@mail:/home/amar# vi /etc/default/spamassassin

Changes as follow

# Change to one to enable spamd
ENABLED=1

# Cronjob
# Set to anything but 0 to enable the cron job to automatically update
# spamassassin's rules on a nightly basis
CRON=1

Save and Exit from file
10E- Enable Database Scan
SpamAssassin under Amavis will only check mail that's determined to be arriving for local delivery. There are a couple of ways to tell Amavis which mails are for local delivery, but here we'll set it up to check the database set up by Postfix Admin. Edit /etc/amavis/conf.d/50-user to look like this:

root@mail:/home/amar# vi /etc/amavis/conf.d/50-user

Changes as follows:

use strict;
 
#
# Place your configuration directives here.  They will override those in
# earlier files.
#
# See /usr/share/doc/amavisd-new/ for documentation and examples of
# the directives you can use in this file
#
 
# Three concurrent processes. This should fit into the RAM available on an
# AWS micro instance. This has to match the number of processes specified
# for Amavis in /etc/postfix/master.cf.
$max_servers  = 3;
 
# Add spam info headers if at or above that level - this ensures they
# are always added.
$sa_tag_level_deflt  = -9999;
 
# Check the database to see if mail is for local delivery, and thus
# should be spam checked.
@lookup_sql_dsn = (
    ['DBI:mysql:database=mail;host=127.0.0.1;port=3306',
     'mail',
     'mailpassword']);
$sql_select_policy = 'SELECT domain from domain WHERE CONCAT("@",domain) IN (%k)';
 
# Uncomment to bump up the log level when testing.
# $log_level = 2;
 
#------------ Do not modify anything below this line -------------
1;  # ensure a defined return

Save and Exit from file

10E-

Next, make sure the ClamAV database is up to date by running fresh clam. It should be:

root@mail:/home/amar# freshclam

10F- Restart services

root@mail:/home/amar# /etc/init.d/spamassassin restart

root@mail:/home/amar# /etc/init.d/clamav-daemon restart

root@mail:/home/amar# /etc/init.d/clamav-daemon restart

root@mail:/home/amar# /etc/init.d/amavis restart

Step 11: - Configure Postfix

Postfix handles incoming mail via the SMTP protocol, and its configuration files have be set up to allow it to integrate with the various other packages we have installed so far. At a high level, we want Postfix to hand off incoming mail to the spam and virus checkers before passing it on to Dovecot for delivery, and to communicate with Dovecot in order to authenticate virtual users who are connecting over SMTP in order to send the email.

11A- Create following files to allow postfix access fo Database.

root@mail:/home/amar# vi /etc/postfix/mysql_virtual_alias_domainaliases_maps.cf

Add following lines

user = mail
password = mailpassword
hosts = 127.0.0.1
dbname = mail
query = SELECT goto FROM alias,alias_domain
  WHERE alias_domain.alias_domain = '%d'
  AND alias.address=concat('%u', '@', alias_domain.target_domain)
  AND alias.active = 1

/etc/postfix/mysql_virtual_alias_maps.cf

user = mail
password = mailpassword
hosts = 127.0.0.1
dbname = mail
table = alias
select_field = goto
where_field = address
additional_conditions = and active = '1'

/etc/postfix/mysql_virtual_domains_maps.cf

user = mail
password = mailpassword
hosts = 127.0.0.1
dbname = mail
table = domain
select_field = domain
where_field = domain
additional_conditions = and backupmx = '0' and active = '1'

/etc/postfix/mysql_virtual_mailbox_domainaliases_maps.cf

user = mail
password = mailpassword
hosts = 127.0.0.1
dbname = mail
query = SELECT maildir FROM mailbox, alias_domain
  WHERE alias_domain.alias_domain = '%d'
  AND mailbox.username=concat('%u', '@', alias_domain.target_domain )
  AND mailbox.active = 1

/etc/postfix/mysql_virtual_mailbox_maps.cf

user = mail
password = mailpassword
hosts = 127.0.0.1
dbname = mail
table = mailbox
select_field = CONCAT(domain, '/', local_part)
where_field = username
additional_conditions = and active = '1'

/etc/postfix/mysql_virtual_sender_login_maps.cf

user = mail
password = mailpassword
hosts = 127.0.0.1
dbname = mail
query = SELECT goto FROM alias WHERE address='%s'

 /etc/postfix/header_checks

/^Received:/                 IGNORE
/^User-Agent:/               IGNORE
/^X-Mailer:/                 IGNORE
/^X-Originating-IP:/         IGNORE
/^x-cr-[a-z]*:/              IGNORE
/^Thread-Index:/             IGNORE

11B- Modify main.cf file

root@mail:/home/amar# vi /etc/postfix/main.cf

Changes as follows

# See /usr/share/postfix/main.cf.dist for a commented, more complete version
 
# The first text sent to a connecting process.
smtpd_banner = $myhostname ESMTP $mail_name
biff = no
# appending .domain is the MUA's job.
append_dot_mydomain = no
readme_directory = no
 
# ---------------------------------
# SASL parameters
# ---------------------------------
 
# Use Dovecot to authenticate.
smtpd_sasl_type = dovecot
# Referring to /var/spool/postfix/private/auth
smtpd_sasl_path = private/auth
smtpd_sasl_auth_enable = yes
broken_sasl_auth_clients = yes
smtpd_sasl_security_options = noanonymous
smtpd_sasl_local_domain =
smtpd_sasl_authenticated_header = yes
 
# ---------------------------------
# TLS parameters
# ---------------------------------
 
# The default snakeoil certificate. Comment if using a purchased
# SSL certificate.
smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
 
# Uncomment if using a purchased SSL certificate.
# smtpd_tls_cert_file=/etc/ssl/certs/example.com.crt
# smtpd_tls_key_file=/etc/ssl/private/example.com.key
 
# The snakeoil self-signed certificate has no need for a CA file. But
# if you are using your own SSL certificate, then you probably have
# a CA certificate bundle from your provider. The path to that goes
# here.
# smtpd_tls_CAfile=/etc/ssl/certs/ca-bundle.crt
 
# Ensure we're not using no-longer-secure protocols.
smtpd_tls_mandatory_protocols=!SSLv2,!SSLv3
 
smtp_tls_note_starttls_offer = yes
smtpd_tls_loglevel = 1
smtpd_tls_received_header = yes
smtpd_tls_session_cache_timeout = 3600s
tls_random_source = dev:/dev/urandom
#smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
#smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
 
# Note that forcing use of TLS is going to cause breakage - most mail servers
# don't offer it and so delivery will fail, both incoming and outgoing. This is
# unfortunate given what various governmental agencies are up to these days.
#
# Enable (but don't force) all incoming smtp connections to use TLS.
smtpd_tls_security_level = may
# Enable (but don't force) all outgoing smtp connections to use TLS.
smtp_tls_security_level = may
 
# See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for
# information on enabling SSL in the smtp client.
 
# ---------------------------------
# TLS Updates relating to Logjam SSL attacks.
# See: https://weakdh.org/sysadmin.html
# ---------------------------------
 
smtpd_tls_exclude_ciphers = aNULL, eNULL, EXPORT, DES, RC4, MD5, PSK, aECDH, EDH-DSS-DES-CBC3-SHA, EDH-RSA-DES-CDC3-SHA, KRB5-DE5, CBC3-SHA
smtpd_tls_dh1024_param_file = /etc/ssl/private/dhparams.pem
 
# ---------------------------------
# SMTPD parameters
# ---------------------------------
 
# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h
# will it be a permanent error or temporary
unknown_local_recipient_reject_code = 450
# how long to keep message on queue before return as failed.
maximal_queue_lifetime = 7d
# max and min time in seconds between retries if connection failed
minimal_backoff_time = 1000s
maximal_backoff_time = 8000s
# how long to wait when servers connect before receiving rest of data
smtp_helo_timeout = 60s
# how many address can be used in one message.
# effective stopper to mass spammers, accidental copy in whole address list
# but may restrict intentional mail shots.
smtpd_recipient_limit = 16
# how many error before back off.
smtpd_soft_error_limit = 3
# how many max errors before blocking it.
smtpd_hard_error_limit = 12
 
# This next set are important for determining who can send mail and relay mail
# to other servers. It is very important to get this right - accidentally producing
# an open relay that allows unauthenticated sending of mail is a Very Bad Thing.
#
# You are encouraged to read up on what exactly each of these options accomplish.
 
# Requirements for the HELO statement
smtpd_helo_restrictions = permit_mynetworks, warn_if_reject reject_non_fqdn_hostname, reject_invalid_hostname, permit
# Requirements for the sender details. Note that the order matters.
# E.g. see http://jimsun.linxnet.com/misc/restriction_order_prelim-03.txt
smtpd_sender_restrictions = permit_mynetworks, reject_authenticated_sender_login_mismatch, permit_sasl_authenticated, warn_if_reject reject_non_fqdn_sender, reject_unknown_sender_domain, reject_unauth_pipelining, permit
# Requirements for the connecting server
smtpd_client_restrictions = reject_rbl_client sbl.spamhaus.org, reject_rbl_client blackholes.easynet.nl
# Requirement for the recipient address. Note that the entry for
# "check_policy_service inet:127.0.0.1:10023" enables Postgrey.
smtpd_recipient_restrictions = reject_unauth_pipelining, permit_mynetworks, permit_sasl_authenticated, reject_non_fqdn_recipient, reject_unknown_recipient_domain, reject_unauth_destination, check_policy_service unix:private/policy-spf, check_policy_service inet:127.0.0.1:10023, permit
smtpd_data_restrictions = reject_unauth_pipelining
# This is a new option as of Postfix 2.10, and is required in addition to
# smtpd_recipient_restrictions for things to work properly in this setup.
smtpd_relay_restrictions = reject_unauth_pipelining, permit_mynetworks, permit_sasl_authenticated, reject_non_fqdn_recipient, reject_unknown_recipient_domain, reject_unauth_destination, check_policy_service unix:private/policy-spf, check_policy_service inet:127.0.0.1:10023, permit
 
# require proper helo at connections
smtpd_helo_required = yes
# waste spammers time before rejecting them
smtpd_delay_reject = yes
disable_vrfy_command = yes
 
# ---------------------------------
# General host and delivery info
# ----------------------------------
 
myhostname = mail.tony.in
myorigin = /etc/hostname
# Some people see issues when setting mydestination explicitly to the server
# subdomain, while leaving it empty generally doesn't hurt. So it is left empty here.
# mydestination = mail.example.com, localhost
mydestination =
# If you have a separate web server that sends outgoing mail through this
# mailserver, you may want to add its IP address to the space-delimited list in
# mynetworks, e.g. as 10.10.10.10/32.
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
mynetworks_style = host
 
# This specifies where the virtual mailbox folders will be located.
virtual_mailbox_base = /var/vmail
# This is for the mailbox location for each user. The domainaliases
# map allows us to make use of Postfix Admin's domain alias feature.
virtual_mailbox_maps = mysql:/etc/postfix/mysql_virtual_mailbox_maps.cf, mysql:/etc/postfix/mysql_virtual_mailbox_domainaliases_maps.cf
# and their user id
virtual_uid_maps = static:150
# and group id
virtual_gid_maps = static:8
# This is for aliases. The domainaliases map allows us to make
# use of Postfix Admin's domain alias feature.
virtual_alias_maps = mysql:/etc/postfix/mysql_virtual_alias_maps.cf, mysql:/etc/postfix/mysql_virtual_alias_domainaliases_maps.cf
# This is for domain lookups.
virtual_mailbox_domains = mysql:/etc/postfix/mysql_virtual_domains_maps.cf
# Used in conjunction with reject_authenticated_sender_login_mismatch to
# verify that the sender is sending with their own address, or with one
# of the aliases mapped to that address.
smtpd_sender_login_maps = mysql:/etc/postfix/mysql_virtual_sender_login_maps.cf
 
# ---------------------------------
# Integration with other packages
# ---------------------------------------
 
# Tell postfix to hand off mail to the definition for dovecot in master.cf
virtual_transport = dovecot
dovecot_destination_recipient_limit = 1
 
# Use amavis for virus and spam scanning
content_filter = amavis:[127.0.0.1]:10024
 
# Settings for checking SPF to cut down spam.
policy-spf_time_limit = 3600s
 
# ---------------------------------
# Header manipulation
# --------------------------------------
 
# Getting rid of unwanted headers. See: https://posluns.com/guides/header-removal/
header_checks = regexp:/etc/postfix/header_checks
enable_original_recipient = no
# getting rid of x-original-to

Save and exit from file

11C- Modify master.cf

root@mail:/home/amar# vi /etc/postfix/master.cf

Changes as follows

# Postfix master process configuration file.  For details on the format
# of the file, see the master(5) manual page (command: "man 5 master" or
# on-line: http://www.postfix.org/master.5.html).
#
# Do not forget to execute "postfix reload" after editing this file.
#
# ==========================================================================
# service type  private unpriv  chroot  wakeup  maxproc command + args
#               (yes)   (yes)   (no)    (never) (100)
# ==========================================================================
smtp      inet  n       -       y       -       -       smtpd
#smtp      inet  n       -       y       -       1       postscreen
#smtpd     pass  -       -       y       -       -       smtpd
#dnsblog   unix  -       -       y       -       0       dnsblog
#tlsproxy  unix  -       -       y       -       0       tlsproxy
 
# SMTP with TLS on port 587. Currently commented.
#submission inet n       -       y       -       -       smtpd
#  -o syslog_name=postfix/submission
#  -o smtpd_tls_security_level=encrypt
#  -o smtpd_sasl_auth_enable=yes
#  -o smtpd_enforce_tls=yes
#  -o smtpd_client_restrictions=permit_sasl_authenticated,reject_unauth_destination,reject
#  -o smtpd_sasl_tls_security_options=noanonymous
  
# SMTP over SSL on port 465.
smtps     inet  n       -       y       -       -       smtpd
  -o syslog_name=postfix/smtps
  -o smtpd_tls_wrappermode=yes
  -o smtpd_sasl_auth_enable=yes
  -o smtpd_tls_auth_only=yes
  -o smtpd_client_restrictions=permit_sasl_authenticated,reject_unauth_destination,reject
  -o smtpd_sasl_security_options=noanonymous,noplaintext
  -o smtpd_sasl_tls_security_options=noanonymous
 
#628       inet  n       -       y       -       -       qmqpd
pickup    unix  n       -       y       60      1       pickup
cleanup   unix  n       -       y       -       0       cleanup
qmgr      unix  n       -       n       300     1       qmgr
#qmgr     unix  n       -       n       300     1       oqmgr
tlsmgr    unix  -       -       y       1000?   1       tlsmgr
rewrite   unix  -       -       y       -       -       trivial-rewrite
bounce    unix  -       -       y       -       0       bounce
defer     unix  -       -       y       -       0       bounce
trace     unix  -       -       y       -       0       bounce
verify    unix  -       -       y       -       1       verify
flush     unix  n       -       y       1000?   0       flush
proxymap  unix  -       -       n       -       -       proxymap
proxywrite unix -       -       n       -       1       proxymap
smtp      unix  -       -       y       -       -       smtp
relay     unix  -       -       y       -       -       smtp
#       -o smtp_helo_timeout=5 -o smtp_connect_timeout=5
showq     unix  n       -       y       -       -       showq
error     unix  -       -       y       -       -       error
retry     unix  -       -       y       -       -       error
discard   unix  -       -       y       -       -       discard
local     unix  -       n       n       -       -       local
virtual   unix  -       n       n       -       -       virtual
lmtp      unix  -       -       y       -       -       lmtp
anvil     unix  -       -       y       -       1       anvil
scache    unix  -       -       y       -       1       scache
#
# ====================================================================
# Interfaces to non-Postfix software. Be sure to examine the manual
# pages of the non-Postfix software to find out what options it wants.
#
# Many of the following services use the Postfix pipe(8) delivery
# agent.  See the pipe(8) man page for information about ${recipient}
# and other message envelope options.
# ====================================================================
#
# maildrop. See the Postfix MAILDROP_README file for details.
# Also specify in main.cf: maildrop_destination_recipient_limit=1
#
maildrop  unix  -       n       n       -       -       pipe
  flags=DRhu user=vmail argv=/usr/bin/maildrop -d ${recipient}
#
# ====================================================================
#
# Recent Cyrus versions can use the existing "lmtp" master.cf entry.
#
# Specify in cyrus.conf:
#   lmtp    cmd="lmtpd -a" listen="localhost:lmtp" proto=tcp4
#
# Specify in main.cf one or more of the following:
#  mailbox_transport = lmtp:inet:localhost
#  virtual_transport = lmtp:inet:localhost
#
# ====================================================================
#
# Cyrus 2.1.5 (Amos Gouaux)
# Also specify in main.cf: cyrus_destination_recipient_limit=1
#
#cyrus     unix  -       n       n       -       -       pipe
#  user=cyrus argv=/cyrus/bin/deliver -e -r ${sender} -m ${extension} ${user}
#
# ====================================================================
# Old example of delivery via Cyrus.
#
#old-cyrus unix  -       n       n       -       -       pipe
#  flags=R user=cyrus argv=/cyrus/bin/deliver -e -m ${extension} ${user}
#
# ====================================================================
#
# See the Postfix UUCP_README file for configuration details.
#
uucp      unix  -       n       n       -       -       pipe
  flags=Fqhu user=uucp argv=uux -r -n -z -a$sender - $nexthop!rmail ($recipient)
#
# Other external delivery methods.
#
ifmail    unix  -       n       n       -       -       pipe
  flags=F user=ftn argv=/usr/lib/ifmail/ifmail -r $nexthop ($recipient)
bsmtp     unix  -       n       n       -       -       pipe
  flags=Fq. user=bsmtp argv=/usr/lib/bsmtp/bsmtp -t$nexthop -f$sender $recipient
scalemail-backend unix  -   n   n   -   2   pipe
  flags=R user=scalemail argv=/usr/lib/scalemail/bin/scalemail-store ${nexthop} ${user} ${extension}
mailman   unix  -       n       n       -       -       pipe
  flags=FR user=list argv=/usr/lib/mailman/bin/postfix-to-mailman.py
  ${nexthop} ${user}
 
# The next two entries integrate with Amavis for anti-virus/spam checks.
amavis      unix    -       -       y       -       3       smtp
  -o smtp_data_done_timeout=1200
  -o smtp_send_xforward_command=yes
  -o disable_dns_lookups=yes
  -o max_use=20
127.0.0.1:10025 inet    n       -       y       -       -       smtpd
  -o content_filter=
  -o local_recipient_maps=
  -o relay_recipient_maps=
  -o smtpd_restriction_classes=
  -o smtpd_delay_reject=no
  -o smtpd_client_restrictions=permit_mynetworks,reject
  -o smtpd_helo_restrictions=
  -o smtpd_sender_restrictions=
  -o smtpd_recipient_restrictions=permit_mynetworks,reject
  -o smtpd_data_restrictions=reject_unauth_pipelining
  -o smtpd_end_of_data_restrictions=
  -o mynetworks=127.0.0.0/8
  -o smtpd_error_sleep_time=0
  -o smtpd_soft_error_limit=1001
  -o smtpd_hard_error_limit=1000
  -o smtpd_client_connection_count_limit=0
  -o smtpd_client_connection_rate_limit=0
  -o receive_override_options=no_header_body_checks,no_unknown_recipient_checks,no_milters
  
# Integration with Dovecot - hand mail over to it for local delivery, and
# run the process under the vmail user and mail group.
dovecot      unix   -        n      n       -       -   pipe
  flags=DRhu user=vmail:mail argv=/usr/lib/dovecot/dovecot-lda -d $(recipient)
 
# Integration with the SPF check package.
policy-spf  unix  -       n       n       -       -       spawn
     user=nobody argv=/usr/bin/policyd-spf

Step 12- Restart all the services:

root@mail:/home/amar# service postfix restart
root@mail:/home/amar# service spamassassin restart
root@mail:/home/amar# service clamav-daemon restart
root@mail:/home/amar# service amavis restart
root@mail:/home/amar# service dovecot restart

Step 13- Test Mail Server:
Use setting below to configure your Email Client.

Use above settings to configure E-mail Client. 

Step 14- Setup SPF (Sender Policy Framework):
Example 1 Allow mail from all hosts listed in the MX records for the domain:

v=spf1 mx -all

Example 2 Allow mail from a specific host:

v=spf1 a:mail.example.com -all

Add the SPF policy agent to Postfix:

Install following package first.

# apt install postfix-policyd-spf-python postfix-pcre

1- If you are using SpamAssassin to filter spam, you may want  edit to

/etc/postfix-policyd-spf-python/policyd-spf.conf to change the HELO_reject and Mail_From_rejectsettings to False. 

root@mail:~# vi /etc/postfix-policyd-spf-python/policyd-spf.conf

Your file looks like below:

debugLevel = 1
TestOnly = 1

HELO_reject = False
Mail_From_reject = False

PermError_reject = False
TempError_Defer = False

Save and exit from file
2- Edit /etc/postfix/master.cf and add the following line

policyd-spf  unix  -       n       n       -       0       spawn
    user=policyd-spf argv=/usr/bin/policyd-spf

Save and exit from file
3-Edit  /etc/postfix/main.cf and add the following line to increase postfix agent policy timeout

policyd-spf_time_limit = 3600

4- Edit /etc/postfix/main.cfand change smtpd_recipient_restrictions list

smtpd_recipient_restrictions = reject_unauth_pipelining, permit_mynetworks, permit_sasl_authenticated, reject_non_fqdn_recipient, reject_unknown_recipient_domain, reject_unauth_destination, check_policy_service unix:private/policy-spf, check_policy_service inet:127.0.0.1:10023, permit

Save and exit from file

5-Restart Postfix

root@mail:~# systemctl restart postfix 

!!!Our E-Mail Server has been configured successfully!!!