Linux Mail Server: Exim4

Whispers Mail Server

Stack

• Web server (Apache)
• Database server (MySQL)
• Email server (MTA) (Exim4)
• IMAP server (Dovecot)
• Webmail server (Roundcube)

Install

• apt-get install apache2-mpm-prefork
  • (Some of these email servers require PHP; PHP is crappy and requires mpm-prefork (the ‘slow’ version of Apache))
• apt-get install mysql-client
  • (should auto-install something like: mysql-common + mysql-client-5.5)
• apt-get install mysql-server
  • (should auto-install something like: mysql-server-5.5 + mysql-server-core-5.5)
• apt-get install exim4
• apt-get install exim4-base
• apt-get install exim4-config
• apt-get install exim4-daemon-heavy
  • (there’s an “exim4-mysql” that might be sufficient to replace this, but I gave up: there are way too many exim4 packages, and no help for installing the “correct” set, so … just pick this and get the lot!)
• apt-get install dovecot-core
• apt-get install dovecot-imapd
• apt-get install dovecot-mysql
• apt-get install roundcube
• apt-get install roundcube-core
• apt-get install roundcube-mysql
• apt-get install roundcube-plugins

Setup

DNS

DNS Registries required by Mail Server

Type	Host	Points to	TTL
A	@	54.154.227.190	1h
CNAME	webmail	@	1h
MX	@	webmail.herrerosolis.com	1h

You need an “MX” record on your DNS server, and it needs to point to your main server where you’ll run your email, web, etc.

Remove MX registries from godaddy email forwarder:
MX:
Host: @; Apunta a:smtp.secureserver.net; Prioridad:30; TTL:1h
Host: @; Apunta a:mailstore1.secureserver.net; Prioridad:50; TTL:1h

SPF

DNS SPF Registry

Type	Host	TXT Value
TXT	@	v=spf1 mx ip4:54.154.227.190 ~all

DMARC

DNS DMARC Registry

Type	Host	TXT Value
TXT	_dmarc	v=DMARC1; p=none  Verification details:      mail-tester.com; dmarc=none header.from=herrerosolis.com     From Domain: herrerosolis.com     DKIM Domain:MIIBIjANBg[...]qCwPwIDAQAB

DKIM

DNS DKIM Registry

Type	Host	TXT Value
TXT	webmail._domainkey	v=DKIM1; k=rsa; p=MIIBIjAN[...]IDAQAB

• Note: DKIM Host must be {selector}._domainkey where {selector} = DKIM_SELECTOR variable from /etc/exim4/conf.d/main/000_localmacros

Apache

/etc/apache2/sites-available/webmail.conf

<VirtualHost *:80>
             ServerAdmin rafael@herrerosolis.com
             Redirect permanent / https://webmail.herrerosolis.com/
         #    DocumentRoot /var/www/rafael
             ServerName webmail.herrerosolis.com
             ServerAlias webmail.herrerosolis.com
             ErrorLog /var/log/apache2/webmail/error.log
         
             # Posible values include: debug, info, notice, warn, error, crit.
             # alert, emerg.
         
             CustomLog /var/log/apache2/webmail/access.log combined
         </virtualHost>
         
         <VirtualHost *:443>
             ServerAdmin rafael@herrerosolis.com
             DocumentRoot /var/lib/roundcube
             ServerName webmail.herrerosolis.com
             ServerAlias webmail.herrerosolis.com
         
             ErrorLog /var/log/apache2/webmail/error.log
         
             # Posible values include: debug, info, notice, warn, error, crit.
             # alert, emerg.
             CustomLog /var/log/apache2/webmail/access.log combined
             SSLEngine on
             SSLCertificateFile /etc/ssl/certs/herrerosolis.crt
             SSLCertificateKeyFile /etc/ssl/private/herrerosolis.key
         </virtualHost>
         

OPTIONAL: Remove TinyMCE

TinyMCE is a WYSIWYG text-editor for HTML emails. I hate it. It had a long history of being insecure, buggy, slow, and hard to use. So I disable it:

Edit /etc/roundcube/apache.conf:

Comment out these lines:
         	#<Directory "/usr/share/tinymce/www/">
         	#      Options Indexes MultiViews FollowSymLinks
         	#      AllowOverride None
         	#      Order allow,deny
         	#      allow from all
         	#</Directory>
         

Create Databases

mysql -u root -p

CREATE DATABASE email_accounts;

USE email_accounts;

CREATE TABLE mailboxes (
             id INT(10) NOT NULL AUTO_INCREMENT PRIMARY KEY,
             domain_id INT(10) NOT NULL,
             local_part VARCHAR(250) NOT NULL,
             password VARCHAR(100) NULL,
             description VARCHAR(250) NULL,
             active TINYINT(1) NOT NULL DEFAULT 0,
             created TIMESTAMP NOT NULL DEFAULT NOW(),
             modified TIMESTAMP NULL
         );
         CREATE TABLE aliases (
             id INT(10) NOT NULL AUTO_INCREMENT PRIMARY KEY,
             domain_id INT(10) NOT NULL,
             local_part VARCHAR(250) NOT NULL,
             goto VARCHAR(250) NOT NULL,
             description VARCHAR(250) NULL,
             active TINYINT(1) NOT NULL DEFAULT 0,
             created TIMESTAMP NOT NULL DEFAULT NOW(),
             modified TIMESTAMP NULL
         );
         CREATE TABLE vacations (
             id INT(10) NOT NULL AUTO_INCREMENT PRIMARY KEY,
             mailbox_id INT(10) NOT NULL,
             subject VARCHAR(250) NOT NULL,
             body TEXT NOT NULL,
             description VARCHAR(250) NULL,
             active TINYINT(1) NOT NULL DEFAULT 0,
             created TIMESTAMP NOT NULL DEFAULT NOW(),
             modified TIMESTAMP NULL
         );
         
         CREATE TABLE domains (
             id INT(10) NOT NULL AUTO_INCREMENT PRIMARY KEY,
             fqdn VARCHAR(250) NOT NULL,
             type ENUM('local','relay') NOT NULL DEFAULT 'local',
             description VARCHAR(250) NULL,
             active TINYINT(1) NOT NULL DEFAULT 0,
             created TIMESTAMP NOT NULL DEFAULT NOW(),
             modified TIMESTAMP NULL
         );
         

Create your first email account and domain

Domain

INSERT INTO domains VALUES(NULL,'herrerosolis.com','local','My personal domain',1,NOW(),NOW());

User

INSERT INTO mailboxes VALUES(NULL,1,'joe',MD5('password - choose a good one'),'My account for joe@herrerosolis.com',1,NOW(),NOW());

Alias

insert into aliases values (null, 1, 'rafa', 'rafael@herrerosolis.com', 'Redirect to me', 1, NOW(), NOW() );

Create a database-account to access the database

grant ALL on email_accounts.* to 'email'@'localhost' identified by 'password';
         flush privileges;
         

http://bradthemad.org/tech/notes/exim_cheatsheet.php

Exim Configuration

• TODO: review daemon ports @/etc/exim4/conf.d/main/9_exim4-config_daemon

dpkg-reconfigure exim4-config

Creates the file: /etc/exim4/update-exim4.conf.conf
Should look like:

# /etc/exim4/update-exim4.conf.conf
         #
         # Edit this file and /etc/mailname by hand and execute update-exim4.conf
         # yourself or use 'dpkg-reconfigure exim4-config'
         #
         # Please note that this is _not_ a dpkg-conffile and that automatic changes
         # to this file might happen. The code handling this will honor your local
         # changes, so this is usually fine, but will break local schemes that mess
         # around with multiple versions of the file.
         #
         # update-exim4.conf uses this file to determine variable values to generate
         # exim configuration macros for the configuration file.
         #
         # Most settings found in here do have corresponding questions in the
         # Debconf configuration, but not all of them.
         #
         # This is a Debian specific file
         
         dc_eximconfig_configtype='internet'
         dc_other_hostnames='[YOUR DOMAIN 1];[YOUR DOMAIN 2]'
         dc_local_interfaces='127.0.0.1;[PUT YOUR SERVER's IP ADDRESS HERE]'
         dc_readhost=''
         dc_relay_domains=''
         dc_minimaldns='false'
         dc_relay_nets=''
         dc_smarthost=''
         CFILEMODE='644'
         dc_use_split_config='true'
         dc_hide_mailname=''
         dc_mailname_in_oh='true'
         dc_localdelivery='maildir_home'

Macros

ADD the following to /etc/exim4/conf.d/main/000_localmacros

MAIN_LOCAL_DOMAINS = @:localhost:dsearch;/etc/exim4/virtual:${lookup mysql{SELECT fqdn AS domain FROM domains WHERE fqdn='${quote_mysql:$domain}' AND type='local' AND active=1}}

ADD the following to /etc/exim4/conf.d/main/01_exim4-config_listmacrosdefs

# List of domains considered local for exim. Domains not listed here
         # need to be deliverable remotely.
         domainlist local_domains = MAIN_LOCAL_DOMAINS
         
         # MySQL because exim4 on Debian doesn't always add this:
         
         MYSQL_SERVER=127.0.0.1
         MYSQL_DB=email_accounts
         MYSQL_USER=email
         MYSQL_PASSWORD=password
         hide mysql_servers = MYSQL_SERVER/MYSQL_DB/MYSQL_USER/MYSQL_PASSWORD

Routers

CREATE the file /etc/exim4/conf.d/router/360_exim4-config_mysqlusers

dovecot_user:
               driver = accept
                 condition = ${lookup mysql{SELECT CONCAT(mailboxes.local_part,'@',domains.fqdn) AS goto FROM domains,mailboxes WHERE \
                            mailboxes.local_part='${quote_mysql:$local_part}' AND \
                            mailboxes.active=1 AND \
                            mailboxes.domain_id=domains.id AND \
                            domains.fqdn='${quote_mysql:$domain}' AND \
                            domains.active=1}{yes}{no}}
              transport = dovecot_delivery

Either DELETE this file, or comment-out all lines /etc/exim4/conf.d/router/400_exim4-config_system_aliases

CREATE this file /etc/exim4/conf.d/router/401_exim4-config_mysql_aliases

### router/401_exim4-config_mysql_aliases
         #################################
         
         # ADAM: This router handles aliasing using the proprietary mysql setup
         #
         # c.f. http://alex.mamchenkov.net/2010/06/24/exim-dovecot-and-mysql/
         #
         
         system_aliases:
              driver = redirect
              allow_fail 
              allow_defer
              data = ${lookup mysql{SELECT aliases.goto AS goto FROM domains,aliases WHERE \
                            (aliases.local_part='${quote_mysql:$local_part}' OR aliases.local_part='@') AND \
                            aliases.active=1 AND \
                            aliases.domain_id=domains.id AND \
                            domains.fqdn='${quote_mysql:$domain}' AND \
                            domains.active=1}}
         

Transports

CREATE / OVERWRITE the file /etc/exim4/conf.d/transport/30_exim4-config_dovecot

### transport/30_exim4-config_dovecot
         #################################
         
         #
         
         dovecot_delivery:
              driver = appendfile
              maildir_format = true
              directory = /var/spool/mail/$domain/$local_part
              create_directory = true
              directory_mode = 0770
              mode_fail_narrower = false
              message_prefix =
              message_suffix =
              delivery_date_add
              envelope_to_add
              return_path_add
              user = mail
              group = mail
              mode = 0660
         

Auth

CREATE the file /etc/exim4/conf.d/auth/20_exim4-config_mysql-authenticator

### AUTHENTICATIOR SECTION
         
         auth_plain:
              driver = plaintext
              public_name = PLAIN
              server_condition = ${lookup mysql{SELECT CONCAT(mailboxes.local_part,'@',domains.fqdn) FROM mailboxes,domains WHERE \
                                mailboxes.local_part=SUBSTRING_INDEX('${quote_mysql:$auth2}','@',1) AND \
                                mailboxes.password=MD5('${quote_mysql:$auth3}') AND \
                                mailboxes.active=1 AND \
                                mailboxes.domain_id=domains.id AND \
                                domains.fqdn=SUBSTRING_INDEX('${quote_mysql:$auth2}','@',-1) AND \
                                domains.active=1}{yes}{no}}
              server_prompts = :
              server_set_id = $auth2
         
         auth_login:
              driver = plaintext
              public_name = LOGIN
              server_condition = ${lookup mysql{SELECT CONCAT(mailboxes.local_part,'@',domains.fqdn) FROM mailboxes,domains WHERE \
                                mailboxes.local_part=SUBSTRING_INDEX('${quote_mysql:$auth1}','@',1) AND \
                                mailboxes.password=MD5('${quote_mysql:$auth2}') AND \
                                mailboxes.active=1 AND \
                                mailboxes.domain_id=domains.id AND \
                                domains.fqdn=SUBSTRING_INDEX('${quote_mysql:$auth1}','@',-1) AND \
                                domains.active=1}{yes}{no}}
              server_prompts = Username:: : Password::
              server_set_id = $auth1

Ports

CREATE the file /etc/exim4/conf.d/main/9_exim4-config_daemon

daemon_smtp_ports = 25 : 465 : 587

http://www.exim.org/exim-html-current/doc/html/spec_html/ch-main_configuration.html
On amazon AWS port 25 might be blocked: https://aws.amazon.com/forms/ec2-email-limit-rdns-request?catalog=true&isauthcode=true

DKIM

Generate DKIM private & public keys:

sudo mkdir /etc/exim4/dkim && cd /etc/exim4/dkim
sudo openssl genrsa -out webmail.herrerosolis.com.dkim.pem 2048
sudo openssl rsa -in webmail.herrerosolis.com.dkim.pem -pubout |sudo tee webmail.herrerosolis.com.dkim.pub

Configure your exim to sign using the DKIM key

Edit /etc/exim4/conf.d/main/000_localmacros and add at the beggining:

DKIM_DOMAIN = ${lc:${domain:$h_from:}}
DKIM_KEY_FILE = /etc/exim4/dkim/webmail.herrerosolis.com.dkim.pem
DKIM_PRIVATE_KEY = ${if exists{DKIM_KEY_FILE}{DKIM_KEY_FILE}{0}}
DKIM_SELECTOR = webmail

DKIM Multiple Domains (TODO)

TODO: Handle multiple domains: https://debian-administration.org/article/718/DKIM-signing_outgoing_mail_with_exim4

DKIM_CANON = relaxed
DKIM_SELECTOR = 20150726

# Get the domain from the outgoing mail.
DKIM_DOMAIN = ${sg{${lc:${domain:$h_from:}}}{^www\.}{}}

# The file is based on the outgoing domain-name in the from-header.
DKIM_FILE = /etc/exim4/dkim/{DKIM_DOMAIN}.pem

# If key exists then use it, if not don't.
DKIM_PRIVATE_KEY = ${if exists{DKIM_FILE}{DKIM_FILE}{0}}

Then run:

update-exim4.conf
service exim4 restart

Dovecot

Make sure you choose split files, can be fixed with:

dpkg-reconfigure dovecot-core

Find mail user uid & gid:

cat /etc/passwd | grep mail

ADD to the file /etc/dovecot/dovecot.conf

protocols = imap
         listen = *, ::

Add to the file /etc/dovecot/conf.d/10-mail.conf

mail_location = maildir:~

ADD to the file /etc/dovecot/conf.d/10-auth.conf

!include auth-sql.conf.ext

ADD to the file /etc/dovecot/dovecot-sql.conf.ext

driver = mysql
         connect = host=127.0.0.1 dbname=email_accounts user=email password=password
         default_pass_scheme = MD5
         
         password_query = SELECT CONCAT(mailboxes.local_part,'@',domains.fqdn) as `user`, mailboxes.password AS `password`,'/var/spool/mail/%d/%n' AS `userdb_home`, [YOUR UID] AS `userdb_uid`, [YOUR GID] AS `userdb_gid` FROM `mailboxes`, `domains` WHERE mailboxes.local_part = '%n' AND mailboxes.active = 1 AND mailboxes.domain_id = domains.id AND domains.fqdn = '%d' AND domains.active = 1
         
         user_query = SELECT '/var/spool/mail/%d/%n' AS `home`, [YOUR UID] AS `uid`, [YOUR GID] AS `gid`

SSL

- Get certificates ej: Lets Encrypt Edit: /etc/dovecot/conf.d/10-ssl.conf

ssl = required
         # Preferred permissions: root:root 0444
         ssl_cert = </etc/ssl/certs/dovecot.pem
         # Preferred permissions: root:root 0400
         ssl_key = </etc/ssl/private/dovecot.pem

Ports

Open ports: IMAP 143 & SSL IMAP 993

Roundcube

EDIT the file /etc/roundcube/main.inc.php

$rcmail_config['default_host'] = '[YOUR MX RECORD]';

Note: replace “[YOUR MX RECORD]” with the MX address you put on your DNS server at the very start. e.g. “mail.my-domain.com”.

In that file, there are instructions on how to make it automatically calculate the address using %n, %d, etc. If your MX records for your different domains follow the same pattern (e.g. they are all “mail.my-domain.com”), and your webmail login addresses all follow the same pattern (e.g. “wemail.my-domain.com”), you can put one string here and it will automatically log people into the right server in every case, based on the URL they visited.

TLS

@/etc/roundcube/config.inc.php

$config['default_host'] = "tls://webmail.herrerosolis.com";

Allow dovecot self-signed certificate

TODO: Lets Encrypt Certificate CA Add to /etc/roundcube/config.inc.php

$config['imap_conn_options'] = array(
           'ssl'         => array(
              'verify_peer'  => false,
              'verify_peer_name'  => false,
              'allow_self_signed' => true,
            ),
          );
         

Enable Password Plugin

• TODO: SQL / password plugin options

@/etc/roundcube/config.inc.php

$config['plugins'] = array('xskin', 'password');

Maximum size for attached documents =

• TODO: Maximum size for attached documents

Fix zipdownload plugin

sudo apt-get install php7.0-zip
sudo apt-get install php7.0-gd

Spamassasin

• TODO: Spamassasin

Roundcube Plugin Installer

cd <roundcube-project-root>
curl -s https://getcomposer.org/installer | php

composer.json-dist to composer.json in your Roundcube root directory

Installing Plugins

https://plugins.roundcube.net/explore/
Then edit your local composer.json file and add the "vendor/plugin" names to the "require" section of the JSON structure. Don't forget to specify the version constraint:

"require" : {
             ...,
             "roundcube/rcsample": ">=0.2.0"
         }

After every change to composer.json run

php composer.phar install

Restart Everithing

/etc/init.d/apache2 restart
         /etc/init.d/exim4 restart
         /etc/init.d/dovecot restart

Exim may output a “paniclog”. If so, read it, fix it – and then manually delete the paniclog file, or else you’ll keep getting fake warnings every time you restart exim.

STARTTLS

https://wiki.debian.org/Exim

Troubleshooting

https://mediatemple.net/community/products/dv/204404634/troubleshooting-common-issues-with-email

Exim

exim4 -bP | grep tls_

test with:

sudo apt-get install swaks
swaks -a -tls -q HELO -s gollum.redactate.com -au test -ap '<>'

Receiving emails

Pick an email address that you added to the “email_accounts” database, and try sending email to it while logged-in to server command-line:

exim -d -bt testname@yourdomain.com

…this will give a COMPLETE list of what exim is doing, and it will tell you every decision it made along the way. It should eventually decide the address is “routeable” and OK it.

• TODO: SOLVED --> bind SMTP to eth0 but not to elastic_ip https://forums.aws.amazon.com/thread.jspa?messageID=776527&#776527

If that looks OK, try sending an email from your normal email account (e.g. your Hotmail / Gmail / Yahoo.com address). Wait a minute, then check the server to see if it crashed trying to receive the email, by checking the logfiles.

Check exim’s logfiles

Exim will put its logfiles in /var/log/exim4. Check for errors using: tail /var/log/exim4/mainlog

(if there’s a lot of errors, you’ll have to cat the whole thing)

If it rejected the email, it will send a bounce-back to your email provider (yahoo/gmail/etc), and it will ALSO put some info into: tail /var/log/exim4/rejectlog test:
https://www.wormly.com

Sending emails

sending emails

…I waited until I had webmail (Roundcube) working before trying this… Any other Exim problems?

If exim is working, but its blocking/rejecting/losing emails, it will “freeze” them after the first failure. You need to “unfreeze” (i.e. retry) each email to see if you’ve fixed the problem. To process all **frozen** messages in the Exim queue use this command:

mailq | grep frozen | awk '{print $3}' | xargs exim -v -M

Here is a list of commands to help: http://bradthemad.org/tech/notes/exim_cheatsheet.php

Test Dovecot

https://wiki2.dovecot.org/TestInstallation

Roundcube

http://www.iredmail.org/docs/debug.roundcubemail.html

DNS

https://mxtoolbox.com/diagnostic.aspx

configuration (mp4)

Resources

http://t-machine.org/index.php/2014/06/27/webmail-on-your-debian-server-exim4-dovecot-roundcube/
https://intodns.com/herrerosolis.com
Another option would be: https://avix.co/blog/creating-your-own-mail-server-amazon-ec2-postfix-dovecot-postgresql-amavis-spamassassin-apache-and-squirrelmail-part-1/

Only two things I might add: 1. In the file /etc/dovecot/conf.d/auth-sql-conf.ext uncomment driver and set it to mysql 2. /etc/dovecot/conf.d/10-mail.conf uncomment first_valid_uid and set it to [your_uid] (ie. 8). If you need to do the same for first_valid_gid

Adding new Domains

1. Add the new domain to to MySQL email_accounts.domains
2. Start creating accounts with the new domain id