WP Mailster


WP Mailster allows your users to be part of a group and communicate by email without having to log into a website.
Similar to programs like Mailman or Listserv this plugin allows you to run a discussion mailing list.

That means that every email sent to a central email address is forwarded to the rest of the members of the list.
When members reply to such emails WP Mailster again forwards them to the other list recipients.
Unlike newsletter plugins this allows true two-way communication via email.

Features include:

  • group communication through email
  • usable with any POP3/IMAP email account
  • recipients are managed by the admin in the WordPress admin area
  • users can subscribe/unsubscribe through widgets on the website
  • all WordPress users can be chosen as recipients, additional users can be stored
  • users can be organized in groups
  • single users or whole groups can be added as recipients of a mailing list
  • replies to mailing list posts can be forwarded to all recipients (or only the sender)
  • email archive for browsing the mails
  • full support of HTML emails and attachments
  • custom headers and footers
  • subject prefixes
  • many more features


  1. Upload the plugin files to the /wp-content/plugins/wp-mailster directory, or install the plugin through the WordPress plugins screen directly.
  2. Activate the plugin through the ‘Plugins’ screen in WordPress
  3. Use the WP Mailster screen to configure the plugin


Installation Instructions
  1. Upload the plugin files to the /wp-content/plugins/wp-mailster directory, or install the plugin through the WordPress plugins screen directly.
  2. Activate the plugin through the ‘Plugins’ screen in WordPress
  3. Use the WP Mailster screen to configure the plugin
How do I send an email?

When you want to use WP Mailster you don’t need to browse to a website, login and do something to send the message there – you just use your favorite mail client.
Simply write an email to the mailing list’s address – and nothing else. So use Gmail, Outlook, Thunderbird, a Webmailer, any way you like – just send it to the mailing list address you have setup in WP Mailster.

Why take the emails so long to be delivered? How can I speed up sending?

WP Mailster is a part of WordPress which is a PHP based web application. That means: it can not act/run without being triggered and it can not run forever when triggered. This is a technical limitation coming from PHP, not from WP Mailster or WordPress.
Triggering means that somebody accesses the site. During the page load Mailster is handling the jobs to do (mail retrieving/sending). Thus mails can only be send/retrieved when somebody is browsing your site, otherwise the delivery is delayed or never done. As your site might not be browsed every few minutes 24×7 we recommend you to use a cronjob that opens the site periodically. We have a guide on our website on how to set that up.

What are send errors?

The send errors are messages your email server is giving back to WP Mailster basically saying “I will not forward this message”. Then WP Mailster sending for some time but eventually stops which is what you see happening.
The cause can be a lot of things, e.g. hitting send limits (per hour/day) or sending email with content that the server does not like.
You need to find out what your email servers are telling WP Mailster. Please follow our troubleshooting guide on our site.


Early days but excellent and first class support

I’ve used the Joomla version of Mailster for many years now and seeing it ported across to WordPress was great news for me as of the 100+ sites I manage, all but one were WordPress and that one was Joomla only because I needed it for Mailster.

Although it is a relatively new WordPress plugin, the concept behind the scenes is sound and well tested so I was happy to become an early adopter. I also knew from personal experience that support for the product would be excellent regardless of whether issues were inherent in the plugin or of my own fault in configuration.

It didn’t take long to get the new install up and running and I’m really pleased with the end product. Thanks Holger for creating the WordPress version

Activation and Database errors

I was hoping to get good result test driving this plugin. Unfortunately, I got an error as soon as I activated (The plugin generated 251 characters of unexpected output during activation. If you notice “headers already sent” messages, problems with syndication feeds or other issues, try deactivating or removing this plugin.) and when I tried to add the first SMTP server (Improperly formatted SQL query). Both of these are within the first minute of install.

For now, this plugin is not ready for production. However, thanks for the energy put in giving back to the community.

The WP e-mailing list plug-in

I have been using Mailster for Joomla several years and have found it excellent. It does exactly what I want. Its support is also great.

I have had an installation of Joomla only because of Mailster.

Now with the same functionality Mailster has also been ported to Word Press. I have tested it and everything seems to work as good as in the Joomla version.

Read all 3 reviews

Contributors & Developers

“WP Mailster” is open source software. The following people have contributed to this plugin.




Release Date – 20th April 2017

  • [Improvement] Set date/time format displayed in email header/footer according to the WordPress installation’s settings
  • [Bug Fix] Only show mailing list settings available in the respective product edition
  • [Bug Fix] Trigger Source setting can be saved
  • [Bug Fix] Language fixes

1.4.13 – 1.4.16 (9th April 2017)

  • [Bug Fix] Fixed Profile shortcode


Release Date – 8th April 2017

  • [Improvement] Email archive in admin has now buttons to removing remaining queue entries and resetting send error count
  • [Bug Fix] Captcha and “add to group” selections can be made in the subscribe widget
  • [Bug Fix] Fixed Profile shortcode in Free edition (Users can subscribe and unsubscribe from lists)


Release Date – 7th March 2017

  • [Feature] CSV import and export of users/email addresses
  • [Bug Fix] Fix some warning messages


Release Date – 19th February 2017

  • [Feature] Introduce shortcodes to display email archives, mailing list and subscription profile
  • [Feature] Add duplicate bulk action to mailing list screen for copying lists
  • [Improvement] Show available shortcodes in dashboard
  • [Bug Fix] Don’t remove white spaces in subject prefix, and plain header/footer
  • [Bug Fix] Remove CSS styling from site area and unneeded styling


Release Date – 2nd February 2017

  • [Bug Fix] Make inline images show up in the email archive message view
  • [Bug Fix] Attachment download in the backend email archive works again


Release Date – 31th January 2017

  • [Bug Fix] Automatically fix remaining DB collation differences


Release Date – 31th January 2017

  • [Bug Fix] Make some important options (e.g. max run time, minimum time between retrieving/sending, …) available in the admin settings GUI


Release Date – 30th January 2017

  • [Improvement] Add search functionality to all admin area lists/tables
  • [Improvement] Improve some GUI elements on the edit mailing list screen
  • [Bug Fix] Existing log file is not overwritten during plugin updates


Release Date – 25th January 2017

  • [Improvement] Show recipient count used in mailing list VS max recipients
  • [Improvement] Better show active GUI elements in edit mailing list screen
  • [Bug Fix] Various small fixes


Release Date – 24th January 2017

  • [Bug Fix] Saving of multiple mailing list settings fixed
  • [Bug Fix] Emails can be deleted in the email archive


Release Date – 23rd January 2017

  • [Improvement] GUI improvements in the mailing list management
  • [Bug Fix] Automatically fixes DB collation differences
  • [Bug Fix] Log file works when WP is installed in subdirectory
  • [Bug Fix] Fixed wrong textual file size representations (KB VS MB)


Release Date – 3rd January 2017

  • Initial release