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 can be managed in the WordPress admin area
  • users can subscribe/unsubscribe through widgets on the website
  • all WP users can be chosen as recipients, additional recipients can be stored (without having to create them as WP users)
  • users can be organized in groups
  • single users or whole groups can be added as recipients of a mailing list
  • replies to mailing list messages 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 WP 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.


Great plugin, and even better support!

I’ve been using this plugin for about six months now, to replace an traditional listserv for an academic organization with a membership of a couple hundred. It works reliably and consistently and is surprisingly customizable considering the challenges of making a listserv work through WordPress. The developer is incredibly responsive, both in making updates and adjustments when it’s called for, and in explaining the technical limitations when a particular feature just isn’t possible.

I wrote a couple code snippets to integrate the listserv with our membership plugin, which means members are automatically added when the join and deleted when their membership expires. We would have never been able to integrate things that seamlessly with something like Google Groups.

Great plug in -great support

WP Mailster is great for setting up group discussions /mailing lists. Attachments come through, and unlike yahoo groups you do not need a specific mail platform to belong to the group.
WP Mailster has been really helpful at setting me up too.

Would definitely recommend the plugin!

Great little plugin…

I grabbed this plugin because I needed a way to set up mailing lists without having to go outside of WordPress. This plugin fills the bill and has several useful features, like list archive viewing and the ability to selectively allow access to specific lists… and so much more. You can also set it up to use your domain’s smtp/imap server rather than use php mail (it uses php mail by default).

The author has done an incredible job with this plugin and has responded quickly whenever I’ve had issues. The value received is worth the amount paid in my book!

FANTASTIC Plugin for E-mail Groups!

After searching and trying several other plugins, Mailster seemed to be my last hope in getting our Community items off of other ListServ providers. Thought I’d take a shot at getting in touch with development to see if they could solve a problem that exists when using WordPress Multi-Site. Talk about a HOME RUN – Support responded to me with a few things, which didn’t solve the issue initially. After working with them over several days, a working plugin was provided that WORKS beautifully with MU! Great JOB guys!!! For those reading this with some frustration maybe, be involved in the plugins you use – if something doesn’t work, don’t just bail – ask. Sure GLAD I did! –William

Definitely the better listserv for WordPress

When it comes to listserv plugins for WordPress, there are just two choices: Mailing Group Listserv and WP Mailster. I bought the first one and ran into limitations and problems. A major limitation was that it didn’t offer CSV imports and exports. A big problem was that the cron-job created new php files in my public_html directory every five minutes. It was horrific.

WP Mailster, on the other hand, handled CSV imports and exports, had a great, well-organized interface, and handled cron-jobs invisibly through their included service. Support has been first rate. Mailster costs more, but it’s worth it.

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

Read all 8 reviews

Contributors & Developers

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


Translate “WP Mailster” into your language.

Interested in development?

Browse the code, check out the SVN repository, or subscribe to the development log by RSS.



Release Date – May 12th, 2018

  • [Improvement] Auto-detect CSV file format on import
  • [Improvement] Language settings fixed to make translation possible
  • [Improvement] Added German translation, thanks Jörg Knörchen
  • [Improvement] Digests can be managed by the admin (Society and Enterprise only)
  • [Bug Fix] Fix counter display for adding/removing list members


Release Date – March 22nd, 2018

  • [Improvement] User interface improvements with more in-app help texts + quick links
  • [Improvement] Remove CC addressing mode because of known negative implications
  • [Bug Fix] Club/Society/Enterprise: Valid licenses are recognized more reliable


Release Date – February 26th, 2018

  • [Bug Fix] Society/Enterprise: Digest frequency can be changed in Profile shortcode
  • [Bug Fix] Fixed typos


Release Date – February 10th, 2018

  • [Improvement] Improve [mst_mailing_lists] and [mst_emails] shortcodes content
  • [Bug Fix] Double Opt-In Subscription through Profile shortcode works
  • [Bug Fix] Fix and remove “log to database” feature


Release Date – December 5th, 2017

  • [Bug Fix] Security Fix XSS (Cross Site Scripting) issue in unsubscribe handler (thank you for your help, Ricardo Sanchez)

1.5.3 / 1.5.4

Release Date – November 19th, 2017

  • [Improvement] Make plugin work in Multiuser / Network site context
  • [Improvement] Recipients names from WP users are coming from first name / last name instead of login names
  • [Improvement] Queue entries can be deleted
  • [Improvement] The shortcode [mst_emails] has new parameter to control the order the messages are dispalyed, e.g. [mst_emails lid=1 order=oldfirst] or [mst_emails lid=1 order=newfirst]
  • [Improvement] Various interface improvements to show #users per list/group and for better navigation
  • [Bug Fix] All list members (recipients) can be removed
  • [Bug Fix] Make unsubscribe (with and without double-opt-out) work
  • [Bug Fix] Subject prefixes can have a blank character at the end
  • [Bug Fix] Unsubscribe URL placeholder (for custom header/footer) works in typcial situations where a text editor adds unneeded http/https before the {unsubscribe} placeholder
  • [Bug Fix] Catch runtime exception in case log file cannot be generated
  • [Bug Fix] Improved logo naming so that browser caching will not prevent correct logo to be displayed after upgrade


Release Date – September 26th, 2017

  • [Feature] Shortcode mst_emails allows to only select a specific mailing list by it’s ID, e.g. [mst_emails lid=2]
  • [Feature] Mailing lists can be duplicated
  • [Improvement] Subscribe / unsubscribe forms work without page reload
  • [Improvement] Introduce reCAPTCHA v2, remove v1
  • [Improvement] PHP 5.3 and PHP 5.4 are supported
  • [Bug Fix] Resolve PHP 7.0 compatibility issue
  • [Bug Fix] Pagination fix for admin lists
  • [Bug Fix] Log file of installation is not written to the root directory
  • [Bug Fix] Fixed typos


Release Date – June 13th, 2017

  • [Improvement] Speed optimization (remove unneeded DB schema checks)
  • [Improvement] Plugin Update Checker updated to latest version
  • [Bug Fix] Pagination fix for threads shortcode
  • [Bug Fix] Added default page size for mails in mails shortcode
  • [Bug Fix] CSV Import: check on PHP’s max_input_vars setting to detect when too much entries would be present to inform the user (and skip the ones too much)


Release Date – May 4th, 2017

  • [Bug Fix] Fix error when mailing lists are saved
  • [Bug Fix] Remove unnecessary “Show User description” setting
  • [Bug Fix] No whitespace in front of text-area settings


Release Date – April 20th, 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 (April 9th, 2017)

  • [Bug Fix] Fixed Profile shortcode


Release Date – April 8th, 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 – March 7th, 2017

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


Release Date – February 19th, 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 – February 2nd, 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 – January 31th, 2017

  • [Bug Fix] Automatically fix remaining DB collation differences


Release Date – January 31th, 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 – January 30th, 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 – January 25th, 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 – January 24th, 2017

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


Release Date – January 23rd, 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 – January 3rd, 2017

  • Initial release