FeaturesWP CloudPricingEE CLIContactMy Account

Features

Team Access & User Permissions

Server Setup & Management

Site Creation & Management

Deployments & Developer Tools

Firewall Protection

Speed & Caching

Backups & Recovery

Logs & Monitoring

Create WP Cloud Sites

All Features

Read Documentation

Install

Installation Guide

FAQ

Roadmap

Explore EE CLI

Resources

Commands

Handbook

Blog

Community

Forum

EasyExperts

Tutorials

Subscribe

Github

CLEAR

Start For Free

Tutorials Emails DKIM with Postfix

Topics

On this page

• Amazon AWS

  • Amazon ELB and multi-domain SAN/SSL Setup
  • Auto Scaling
  • Change Instance Type in AutoScaling

• Backup

  • Duplicity + Amazon S3

• Benchmark

  • apachebench
  • httperf
  • Siege

• CDN

  • Amazon Cloudfront CDN with W3 Total Cache WordPress
  • CDN.NET Configuration with W3 Total Cache Wordpress
  • CDN77 Configuration with W3 Total Cache WordPress

• Composer and WordPress

  • Getting Started
  • Git and File-System Layout (non-default setup)
  • Version Constraints
  • Managing Themes and Plugins (for entire WordPress site)
  • Updating Themes and Plugins (for entire WordPress site)
  • Adding Composer Support to Your Own Themes and Plugins (for developers)
  • Using Composer to Manage Own Theme/Plugin Dependencies (for developers)

• Docker and WordPress [WIP]

  • Kubernetes

    • WordPress with Kubernetes using Minikube and Helm on localhost (MacOS)

• Git

  • Git – Resolve Merge Conflicts
  • First time Git setup
  • Forking the Git
  • Mandatory stages in Git

• Gitlab

  • Gitlab-CE
  • gitlab-ci-multi-runner

• KVM

  • Convert qcow2 to raw format
  • Enable virtio for existing VM's

• Mac

  • Brew'ing PHP, MySQL & Nginx on Mac OS X

• Monitoring

  • Latest Monit setup on Ubuntu
  • NewRelic Setup for Ubuntu Server with PHP, FPM, Nginx and MySQL

• node.js

  • Installing ghost with nginx proxy-cache
  • Latest node.js & npm installation on Ubuntu 12.04

• Plesk

  • List Mailboxes Storage and Passwords

• Redis

• Standards

  • PHP

    • Code Sniffer

• Vagrant

• wpcli

  • Finding a faulty plugin
  • wp profile command

• Linux

  • Assigning Multiple IP Addresses to Single LAN Card
  • Disable IPv6 on Ubuntu 12.04
  • dsh – distributed shell
  • fdupes – find & replace duplicate files with hardlinks
  • GPG Keys Cheatsheet
  • Increase "Open Files Limit"
  • kill all php, nginx, mysql or any kind of processes
  • Passwordless Authentication for SSH
  • Screen
  • search replace in multiple files useing grep xargs sed
  • Setup sftp
  • sysctl.conf
  • Timezone Sync
  • Using Google Public DNS on Ubuntu Server
  • Using openssl to match private key, cerificate and CSR
  • Configure Postfix to Use Gmail SMTP on Ubuntu
  • Logrotate Example for Custom Logs
  • PHP 5.5, MySQL, Postfix, Nginx and WordPress on Ubuntu
  • Serverdensity
  • Upgrade Ubuntu 10.04 to 12.04
  • Using find and sed to replace strings in multiple files
  • Webmin

• Apache – Turn On/Off Directory Listing

• Enabling FastCGI on MediaTemple

• Manage SVN Users with htpasswd

• Mysql

  • .my.cnf – mysql user & password
  • Analyse slow-query-log using Anemometer
  • Improving MySQL Query Cache
  • MySQL Query Profiling
  • Reset MySQL root password
  • tuning-primer.sh – an alternative for mysqltuner
  • Using MariaDB 10
  • Install/Upgrade to MySQL 5.6 on Ubuntu 12.04 LTS
  • Change WordPress Domain Name
  • Character Sets and Collations
  • Enable innodb_file_per_table
  • Enable Remote Access (Grant)
  • Installing Percona Toolkit
  • Using tmpfs for temporary folder creation
  • YARPP and InnoDB
  • Convert MyISAM to InnoDB
  • Using tmpfs for mysqldump & mysqlimport
  • Convert from INNODB to MYISAM
  • Analyse slow-query-log using mysqldumpslow & pt-query-digest
  • mysqlcheck with cron to optimize automatically
  • Using MySQLTuner to Optimize MySQL configuration

• Emails

  • Checking FQDN, Reverse-DNS/PTR, MX record

  • Clients

    • Apple Mail
    • Mozilla Thunderbird

  • DKIM with Postfix

  • Postfix Queue Management

  • RoundCube

    • Forwarding all mails to other email id

  • Server Setup

    • Packages & Conventions

    • Postfix, Dovecot, ViMbAdmin, RoundCube

    • Amavis, Spamassassin & ClamAV Setup

    • Sieve Mail Filtering Setup

    • Mail-Server Testing

      • Antivirus Tests
      • IMAP Tests
      • POP Tests
      • SMTP Tests
      • Spam Tests

    • Mailserver Port Numbers

  • Setup OpenDKIM

  • SPF Records

  • swaks – SMTP test tool

  • Using larch for mail transfer between imap/gmail servers

  • Debugging Postfix Config, Mail Logs & more

  • Increasing Attachment Size in Posfix

• Nginx

  • Adding $upstream_cache_status in HTTP Response Headers

  • Amazon Elastic Load Balancer and Forwarding Real-IP Nginx

  • Block wp-login.php bruteforce attack

  • Configuring HTTP/2 Server Push

  • Enable gzip compression

  • fail2ban

  • Filter query string for Redis-Nginx cache

  • Let's Encrypt with EasyEngine

  • Nginx's Open file cache

  • Serving fonts with correct mime types

  • SSL – PCI compliance and performance optimization

  • Troubleshooting

    • Error: pcre_compile() failed: unrecognized character after
    • [emerg]: bind() to 0.0.0.0:80 failed (98: Address already in use)

  • Tweaking fastcgi-buffers

  • Using $upstream_cache_status in access.log

  • Using Pagespeed

  • Weak Diffie Hellman Logjam Attack Fix

  • Website access restriction using nginx

  • Enable Nginx Status Page

  • Forwarding Visitor's Real-IP + Nginx Proxy/Fastcgi backend correctly

  • Parsing access.log and error.logs using linux commands

  • Debugging Nginx Configuration

  • Nginx config for www to non-www and non-www to www redirection

  • Optimizing Nginx Configuration

  • Rewrite Rules for vBulletin SEO-friendly permalinks

• PHP

  • Directly connect to PHP-FPM
  • Generating core-dump for php5-fpm
  • GeoIP
  • Having php5 and php7 on same system.
  • Install Xdebug and configure it with webgrind
  • Installation of PHP Code Review Tools
  • memcache
  • PHP's Zend Opcache Config & Web Viewer
  • Setting Sqlite support with PHP
  • Using HHVM with PHP-FPM Fallback
  • Using Redis for PHP Sessions on Ubuntu Server
  • Installing PhpMyAdmin Quickly
  • Moving PHP's session storage to tmpfs
  • Install Xdebug and configure it with Netbeans
  • Nginx – Enable PHP-FPM Status Page
  • PHP-FPM: Socket vs TCP/IP and sysctl tweaking
  • APC Cache Optimization & Monitoring Using Web Interface
  • Checking if PHP/WordPress can send mails
  • Debugging PHP Scripts Using slow_log and more
  • Increase file upload size limit in PHP-Nginx
  • Increase PHP script execution time with Nginx

• ActiveCollab with Nginx + APC Cache

• WordPress

  • Performance Optimization
  • Remove Query string of css/js files
  • Setup ElasticSearch with ElasticPress
  • Using Redis for WordPress Object-Cache
  • WooCommerce Window Shopping Caching Technique
  • Moving WordPress To New Server (Faster)
  • Better wp-cron using linux's crontab
  • 404 error- Page not Found!!!
  • Debugging WordPress with Nginx

Install DKIM

Edit Config files

DKIM config

Postfix file

DKIM Key Generation

DNS Record Setup

Start Signing

Testing DKIM setup for correctness

Verify DNS Records for DKIM Setup

Verify DKIM Signing

DKIM with Postfix

If mails from your web-server/webapp is having delivery issues, DKIM (DomainKeys Identified Mail) can help you big time.

Its highly recommended to use DKIM for outgoing emails even if your server is not running any kind of mail-hosting.

Install DKIM

			apt-get install opendkim opendkim-tools
		

Edit Config files

DKIM config

Open dkim config file vim /etc/opendkim.conf

Add following lines towards end. Make sure you replace example.com with your domain/subdomain.

			Domain                  example.com
KeyFile                 /etc/postfix/dkim.key
Selector                mail
SOCKET                  inet:8891@localhost
		

Next open dkim defaults file vim /etc/default/opendkim

Change default socket path by adding a line like below:

			SOCKET="inet:8891@localhost"
		

Postfix file

Open postfix main config file vim /etc/postfix/main.cf

Add following lines towards end.

			# DKIM
milter_default_action = accept
milter_protocol = 2
smtpd_milters = inet:localhost:8891
non_smtpd_milters = inet:localhost:8891
		

DKIM Key Generation

Run following commands with mail and example.com matching values used in /etc/opendkim.conf file in earlier step.

			opendkim-genkey -t -s mail -d example.com
		

This command will generate mail.private and mail.txt file. mail.private is private key that will be used to sign outgoing emails. Move it to the location we specified earlier in /etc/opendkim.conf

			cp mail.private /etc/postfix/dkim.key
		

DNS Record Setup

Next, you need to create a TXT record on DNS end. Just check content of mail.txt file created by opendkim-genkey command we ran above.

			cat mail.txt
		

You will see something like below:

			mail._domainkey IN TXT "v=DKIM1; k=rsa; t=y; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDYv84GSl0Xp2CrPdFqMZ9ShBDi9Pal9XpfIf7asEENxLRdIka3TONpqtrcCKksROJBNh2G3OVGuoGJ1watQGT46B+zQtjcCI67+WiTlb2D98s1UV3KO7oi/0QH/lH8DzUmrGJUIy3ZBQ9mIu1t6YDyi8y3hlhTILHW7G4HV/VtwQIDAQAB" ; ----- DKIM key mail for example.com
		

TXT record will require NAMS & VALUE.

Use mail._domainkey for NAME and long string in quotes starting from v=DKIM1 as VALUE.

Below is a sample screenshot for a TXT record. User-interface on your end might differ.

If you are editing a previous DNS record, it might take sometime for changes to propogate.

Start Signing

Once al config & setup done, you need to start DKIM service and restart postfix.

			service opendkim start
service postfix restart
		

Testing DKIM setup for correctness

Anything we do, specially for first time, must end with successful testing!

There are many tools for testing. I will mention few of them below.

Verify DNS Records for DKIM Setup

This will ONLY verify if your TXT record is created successfully.

dig command

Classic and easy. You must be having this already. Running…

			dig mail._domainkey.example.com TXT
		

should return a response like…

			;; ANSWER SECTION:
mail._domainkey.exmaple.com. 86400 IN   TXT "v=DKIM1\;" "k=rsa\;" "t=y\;" "p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDYv84GSl0Xp2CrPdFqMZ9ShBDi9Pal9XpfIf7asEENxLRdIka3TONpqtrcCKksROJBNh2G3OVGuoGJ1watQGT46B+zQtjcCI67+WiTlb2D98s1UV3KO7oi/0QH/lH8DzUmrGJUIy3ZBQ9mIu1t6YDyi8y3hlhTILHW7G4HV/VtwQIDAQAB"
		

Web-based Record Check

You can use http://www.protodave.com/tools/dkim-key-checker/

Use selector  mail and domain example.com there.

Verify DKIM Signing

Test #1 – Email-based

If you have setup keys correctly then you should pass this test.

You can test by simply sending an email to autorespond+dkim@dk.elandsys.com or check-auth2@verifier.port25.com

It’s better to use swaks tools for mail-testing (apt-get install swaks).

			swaks -t check-auth2@verifier.port25.com -f me@example.com
		

Replace me@example.com with your mail id where you would like to receive test results.

Test #2 – Web-based

Better choice will be to use a service like http://www.mail-tester.com/  which gives you a temporary email ID and web-interface to see what happens to the email on receiving end!

For WordPress, its better to test using Check Email plugin as you will get better picture of what happens to mail sent from WordPress!

Mozilla Thunderbird

PREVIOUS

Postfix Queue Management

NEXT

Comments

1. 

   wayne

   January 6, 2014

   Good day

   I used

   Domain *
   KeyFile /etc/postfix/dkim.key
   Selector mail

   in /etc/opendkim.conf to use the same key for multiple domains

   External link to help.ubuntu.comhttps://help.ubuntu.com/community/Postfix/DKIM#Common_errors_and_fixes
   and added “no_milters” to /etc/postfix/master.cf

   made this line:
   -o receive_override_options=no_header_body_checks,no_unknown_recipient_checks

   look like:
   -o receive_override_options=no_header_body_checks,no_unknown_recipient_checks,no_milters

   This prevented opendkim signing messages twice.

   I am curious whether this is sane or not. Remember laziness counts!

   Enjoy your day and thank you for your time.

   1. 

      Rahul Bansal

      January 7, 2014

      I never used DKIM like above but in another use-case, I used no_milter to avoid double processing.

      If it’s working, it must be fine! 😉

2. 

   Niklas K

   January 27, 2014

   Thanks so much. I was stuck with other tutorials at entering the Information into DNS.
   Helped me great!!

3. 

   Joe

   February 15, 2014

   Hello,

   thank you for this usefull tutorial 😀

   i used to create my DKIM

   in External link to www.protodave.comhttp://www.protodave.com/tools/dkim-key-checker/ with selector mail is passed ok!

   but in the External link to www.mail-tester.comhttp://www.mail-tester.com/ web site i have always (-1) for this.

   i have to use selector named default?
   or change something else in settings?

   thank you 🙂

   1. 

      Rahul Bansal

      February 17, 2014

      You need to make sure selector and DNS TXT name match. If there is a mismatch above testing tool may throw error.

4. 

   Evan

   March 5, 2014

   Hi there! I followed your setup to the letter and I am no longer able to send mails. I get a transport error on the Milter serve. Have you got any idea why?

   “postfix/cleanup[3127]: warning: invalid transport name: “inet in Milter service: “inet:localhost:8891″”

   1. 

      Rahul Bansal

      March 7, 2014

      Check if your postfix config matches – External link to rtcamp.comhttps://rtcamp.com/tutorials/mail/dkim-postfix-ubuntu/#postfix-file ?

      1. 

         Evan

         March 10, 2014

         Ok So I reset all the config and now it’s working. However, I have another blockage: when I do a HELO test via smtp on the server side (i.e. telnet localhost 25) I can send mails. However, I added my distant application site to mynetworks in order to allow smtp relays. The problem is that the HELO test seems to go well and the message is queued, but the server does nothing. The log file gives no error message either… Any idea?

         1. 

            Rahul Bansal

            March 14, 2014

            For HELO issue, please check postfix error log.

5. 

   Umesh Kumar

   March 9, 2014

   t=y in DKIM Key enables test mode, so even if you have DKIM, you are telling it to ignore. Also you can see the mails, you’ll get test mode in it. (when you click show original, it displays dkim =pass (test mode) ).
   Ref; External link to goo.glhttp://goo.gl/j3Fjbp, External link to goo.glhttp://goo.gl/sbSI82

   1. 

      Rahul Bansal

      March 14, 2014

      Very usrful info! Thanks for sharing. 🙂

Features

• Server Setup & Management
• Site Creation & Management
• Create WP Cloud Sites
• Speed & Caching
• Firewall Protection
• Backups & Recovery
• Logs & Monitoring
• Deployments & Developer Tools
• Team Access & User Permissions

Useful Links

• EE Dashboard Docs
• My Account
• Blog
• Contact
• About

Product

• EE Dashboard
• EE CLI (OpenSource)

Other Products

• GoDAM

Subscribe for curated product updates, tips, and announcements.

"*" indicates required fields

LinkedIn

This field is for validation purposes and should be left unchanged.

Email*

SIGN ME UP

Δ

© rtCamp, since 2009. All rights reserved.

• T&Cs
• Refund Policy
• Support Policy
• Terms of Use & Privacy Policy

Powered by