{"id":2544,"date":"2013-11-18T13:03:44","date_gmt":"2013-11-18T19:03:44","guid":{"rendered":"https:\/\/secure.rosehosting.com\/blog\/?p=2544"},"modified":"2025-07-18T06:46:46","modified_gmt":"2025-07-18T11:46:46","slug":"mailserver-with-virtual-users-and-domains-using-postfix-and-dovecot-on-a-centos-6-vps","status":"publish","type":"post","link":"https:\/\/www.rosehosting.com\/blog\/mailserver-with-virtual-users-and-domains-using-postfix-and-dovecot-on-a-centos-6-vps\/","title":{"rendered":"Mailserver with virtual users and domains using Postfix and Dovecot on a CentOS 6 VPS"},"content":{"rendered":"
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Status: This OS is no longer supported<\/h5>\n\n\n\n

This article, “Mailserver with virtual users and domains using Postfix and Dovecot on a CentOS 6 VPS,” covers a version of CentOS that reached end of life (EOL). It is no longer supported. As such, this guide is no longer maintained. If you are currently operating a server running CentOS 6, we highly recommend contacting RoseHosting’s fully managed support<\/a>. They can upgrade or migrate you to a supported version of AlmaLinux.<\/em><\/p>\n\n\n\n\n\n\n

\"mailserver-with-virtual-users-and-domains-using-postfix-and-dovecot-in-centos-6\"<\/a>The following article will show you how to install and run a simple POP3<\/strong>\/IMAP<\/strong>\/SMTP<\/strong> mail server in your CentOS VPS<\/a> using virtual users and domains<\/strong> with Postfix <\/strong>and Dovecot<\/strong><\/p>\n

What is Postfix?<\/strong> It is a drop in replacement for the old and mature Sendmail. Postfix also attempts to be very fast, easy to administer, and secure.<\/p>\n

What is Dovecot?<\/strong> It is an open-source IMAP and POP3 server for *NIX-like systems, written primarily with security in mind.<\/p>\n

\u00a0<\/p>\n

PRE-REQ<\/h3>\n

You may want to check if your hostname\/domainname is a valid FQDN (fully qualified domain name) and it has a valid MX DNS record.<\/p>\n

## if ! type -path \"dig\" > \/dev\/null 2>&1; then yum install bind-utils -y; fi<\/pre>\n
## DOMAIN=mydomain.com\n## NSHOSTS=( \"$(dig @4.2.2.2 +short MX ${DOMAIN}|sort -n|cut -d' ' -f2)\" )\n## for NS in ${NSHOSTS[@]}; do printf \"%-15s => %-s\\n\" \"$(dig @4.2.2.2 +short A ${NS})\" \"${NS}\"; done\n## unset DOMAIN NSHOSTS<\/pre>\n
UPDATE THE SYSTEM<\/h3>\n
## screen -U -S mailserver-screen\n## yum update<\/pre>\n
SET-UP SYSTEM USER<\/h3>\n
Create a group used for virtual mailboxes<\/p>\n
## groupadd vmail -g 2222<\/pre>\n
Create a user used for virtual mailboxes<\/p>\n
## useradd vmail -r -g 2222 -u 2222 -d \/var\/vmail -m -c \"mail user\"<\/pre>\n
INSTALL POSTFIX<\/h3>\n
## yum remove exim sendmail\n## yum install postfix cronie<\/pre>\n
Edit postfix main.cf<\/code> configuration file<\/p>\n
## cp \/etc\/postfix\/main.cf{,.orig}\n## vim \/etc\/postfix\/main.cf<\/pre>\n
queue_directory = \/var\/spool\/postfix\ncommand_directory = \/usr\/sbin\ndaemon_directory = \/usr\/libexec\/postfix\ndata_directory = \/var\/lib\/postfix\nmail_owner = postfix\nunknown_local_recipient_reject_code = 550\nalias_maps = hash:\/etc\/postfix\/aliases\nalias_database = $alias_maps\n\ninet_interfaces = all\ninet_protocols = ipv4\nmydestination = $myhostname, localhost.$mydomain, localhost\n\ndebug_peer_level = 2\ndebugger_command =\n         PATH=\/bin:\/usr\/bin:\/usr\/local\/bin:\/usr\/X11R6\/bin\n         ddd $daemon_directory\/$process_name $process_id & sleep 5\n\nsendmail_path = \/usr\/sbin\/sendmail.postfix\nnewaliases_path = \/usr\/bin\/newaliases.postfix\nmailq_path = \/usr\/bin\/mailq.postfix\nsetgid_group = postdrop\nhtml_directory = no\nmanpage_directory = \/usr\/share\/man\nsample_directory = \/usr\/share\/doc\/postfix-2.6.6\/samples\nreadme_directory = \/usr\/share\/doc\/postfix-2.6.6\/README_FILES\n\nrelay_domains = *\nvirtual_alias_maps=hash:\/etc\/postfix\/vmail_aliases\nvirtual_mailbox_domains=hash:\/etc\/postfix\/vmail_domains\nvirtual_mailbox_maps=hash:\/etc\/postfix\/vmail_mailbox\n\nvirtual_mailbox_base = \/var\/vmail\nvirtual_minimum_uid = 2222\nvirtual_transport = virtual\nvirtual_uid_maps = static:2222\nvirtual_gid_maps = static:2222\n\nsmtpd_sasl_auth_enable = yes\nsmtpd_sasl_type = dovecot\nsmtpd_sasl_path = \/var\/run\/dovecot\/auth-client\nsmtpd_sasl_security_options = noanonymous\nsmtpd_sasl_tls_security_options = $smtpd_sasl_security_options\nsmtpd_sasl_local_domain = $mydomain\nbroken_sasl_auth_clients = yes\n\nsmtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination\nsmtpd_relay_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination<\/pre>\n
Create vmail_domains<\/code> configuration file. This is where you add your virtual domains.<\/p>\n
## vim \/etc\/postfix\/vmail_domains<\/pre>\n
mydomain.com            OK\nmy-otherdomain.com      OK<\/pre>\n
Create vmail_mailbox<\/code> configuration file. This is where you define your mailboxes.<\/p>\n
## vim \/etc\/postfix\/vmail_mailbox<\/pre>\n
info@mydomain.com           mydomain.com\/info\/\ninfo@my-otherdomain.com     my-otherdomain.com\/info\/<\/pre>\n
Create vmail_aliases<\/code> configuration file. This is where you define your virtual aliases.<\/p>\n
## vim \/etc\/postfix\/vmail_aliases<\/pre>\n
info@mydomain.com           info@mydomain.com\ninfo@my-otherdomain.com     foo@bar.tld<\/pre>\n
Hash the configuration files<\/p>\n
<pre>## postmap \/etc\/postfix\/vmail_domains ## postmap \/etc\/postfix\/vmail_mailbox ## postmap \/etc\/postfix\/vmail_aliases<\/p>\n
## touch \/etc\/postfix\/aliases\n## vim +\/submission \/etc\/postfix\/master.cf<\/pre>\n
submission inet n       -       n       -       -       smtpd<\/pre>\n
INSTALL DOVECOT<\/h3>\n
## yum install dovecot<\/pre>\n
Edit dovecot <code>dovecot.conf configuration file<\/p>\n
## cp \/etc\/dovecot\/dovecot.conf{,.orig}\n## vim \/etc\/dovecot\/dovecot.conf<\/pre>\n
listen = *\nssl = no\nprotocols = imap lmtp\ndisable_plaintext_auth = no\nauth_mechanisms = plain login\nmail_access_groups = vmail\ndefault_login_user = vmail\nfirst_valid_uid = 2222\nfirst_valid_gid = 2222\n#mail_location = maildir:~\/Maildir\nmail_location = maildir:\/var\/vmail\/%d\/%n\n\npassdb {\n    driver = passwd-file\n    args = scheme=SHA1 \/etc\/dovecot\/passwd\n}\nuserdb {\n    driver = static\n    args = uid=2222 gid=2222 home=\/var\/vmail\/%d\/%n allow_all_users=yes\n}\nservice auth {\n    unix_listener auth-client {\n        group = postfix\n        mode = 0660\n        user = postfix\n    }\n    user = root\n}\nservice imap-login {\n  process_min_avail = 1\n  user = vmail\n}<\/pre>\n
Create a virtual user’s configuration file passwd<\/code>. This is where usernames and password hashes will be stored.<\/p>\n
## touch \/etc\/dovecot\/passwd\n## doveadm pw -s sha1 | cut -d '}' -f2\n\n## vim \/etc\/dovecot\/passwd<\/pre>\n
info@mydomain.com:DOzcsKI8HY0bg8LAuz0DPKwS3WA=<\/pre>\n
## chown root: \/etc\/dovecot\/passwd\n## chmod 600 \/etc\/dovecot\/passwd<\/pre>\n
START SERVICES<\/h3>\n
## chkconfig postfix on\n## chkconfig dovecot on\n## service postfix restart\n## service dovecot restart<\/pre>\n
TEST THE SET-UP<\/h3>\n
Open your favorite e-mail client and configure it to use the newly created info@mydomain.com<\/code> account. Try to send\/receive an email. If you experience any issues, check if there’s something logged in \/var\/log\/maillog<\/code><\/p>\n
You can also use swaks<\/code> to test your SMTP server, for example:<\/p>\n
swaks --to support@mydomain.com --from email@address.net<\/pre>\n
more information about swaks<\/code> you can find at man swaks<\/code><\/p>\n
ADD ANOTHER ACCOUNT<\/h3>\n
Set up the account’s mailbox<\/p>\n
## vim \/etc\/postfix\/vmail_mailbox\n...\nsupport@mydomain.com           mydomain.com\/support\/<\/pre>\n
set-up account’s alias(es)<\/p>\n
## vim \/etc\/postfix\/vmail_aliases\n...\nsupport@mydomain.com           support@mydomain.com<\/pre>\n
Postmap configuration files and restart Postfix<\/p>\n
## postmap \/etc\/postfix\/vmail_mailbox\n## postmap \/etc\/postfix\/vmail_aliases\n## service postfix restart<\/pre>\n
Generate password hash and add username:password-hash to the passwd file.<\/p>\n
## doveadm pw -s sha1 | cut -d '}' -f2\n## vim \/etc\/dovecot\/passwd\n...\nsupport@mydomain.com:DOzcsKI8HY0bg8LAuz0DPKwS3WA=<\/pre>\n
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This is a simple, yet very robust mail server set-up on a CentOS 6 VPS<\/a> which supports SMTP and IMAP without SSL, webmail, anti-spam, anti-virus, filter rules, opendkim, etc. However, in the next few related articles, we will be adding additional features to the setup to make it even more powerful, so stay tuned.<\/p>\n