WP Mailster


True two-way group communication over email

Allow 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

Note: This version of WP Mailster is FREE and limited in terms of number of lists and subscribers per list. Additional features such as captcha protection, double opt-in, email filtering, configurable event notifications, and many others are available in the premium editions.


  • The dashboard provides an overview of the overall status (mailing list, #emails etc)
  • All emails (that are forwarded to the subscribers) are also stored in an email archive in the admin section
  • Mailing list settings, general settings
  • Mailing list settings, mailbox (incoming email)
  • Mailing list settings, mailbox: choose from some pre-configured servers or use your own (what most users do)
  • Mailing list settings, sender settings (outgoing email)
  • Mailing list settings, mail content
  • Mailing list settings, list behaviour
  • Manage your recipients (per list and/or via custom groups)
  • Add members to your list (both WP users and users outside of WP are possible)


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.


We've been using WP-Mailster for about 2 years. During that time we've encountered various issues that caused the plugin to fail or not not perform entirely as expected because of local server setup issues . Each time the WP-Mailster staff worked diligently to resolve our issues. We ran into another problem this month and once again they stepped up. No software runs entirely trouble free so it's nice to have support that is there for you.
2022年11月24日 1 回复
About 7 years ago I searched for a ListServ application to be used on a WordPress membership site --- I could not find one other than the Joomla version of this plugin. Using a sub-domain and the Joomla platform, it did its job flawlessly for the last 6 or 7 years. For this period, I manually had to synchronize the WordPress membership with the Joomla database. Now, as with any other software, I rebuild and updated the WordPress membership website to WordPress 6.1, updated the server to PHP 8.1. and installed the WordPress version WP Mailster (enterprise, because I need a license for a second website) and ditched the old Joomla based mail list server. It was an effortless crossover. WP Mailster does what it is intended for, its interfaces are logical and support is given speedily. The best part, no third party is involved to disseminate the emails.
This plugin is very feature-rich and powerful. It is really one of the only ones of its kind. I had a couple of issues when configuring it and testing it, but I received very fast and helpful replies from support. The plugin is perfect for many usage cases. Mine is simply that I have a WordPress website that used to use Google Groups. Google Groups is great, but everyone needs to have a Google account to access the web-based interface. Also, there is no easy way to sync Google Groups membership with your website's member data. Trust me, I have tried, but none of them work very well. Thanks to the developer for this great creation! Keep up the nice work.
We have run Listservs on two member association websites for 7 years. We have used outside/non-wordpress vendors. We have used and tested other Wordpress plugins. We even built our own Wordpress solution that worked for us for a while. We've been working with WP Mailister now for about a year, and it has been by far the best solution for us. Simple set up. All of the options and features we could ever need. Excellent support and customer service. Comprehensive documentation. And it's so affordable. For the users, it is simple to use, and we love having the user-facing email archive. I would highly recommend this plugin if you're looking for a Wordpress listserv solution.
We use the WP-Mailster Plug-in for our camera club emails. We use it in a number of different ways. 1. Mailing out to members any news about website updates and changes. 2, Distributing our newsletter [replies only go to sender] & 3, as a ListServ for our Committee emails and email discussions [replies go all to whole group]. I was unable to find any other plug-in that offered this level of flexibility, it was straightforward to implement and requires no maintenance. It is updated regularly and provides detailed logs to enable me to track down and managed undeliverable or bounced emails. Support is always timely and excellent. WakefieldCameraClub.org.uk
Hi, After a year of searching (testing and subscribing to services) in order to replace the "mailman" product, which we gave in my case, some problems, I found this plugin, which solves what I need (enterprise edition). Doubts and possible questions about how to approach the service have been resolved quickly via email: fast, effective and efficient support. I encourage the developer to continue with his style of support that has sometimes gone beyond what he expected and to grow the project, which will surely be to the satisfaction of its customers. Joan


“WP Mailster” 是开源软件。 以下人员对此插件做出了贡献。


“WP Mailster”插件已被翻译至2种本地话语言。 感谢所有译者为本插件所做的贡献。

将“WP Mailster”翻译成您的语言。





Release Date – January 9th, 2023

  • [Improvement] Better warn about non-supported special characters in the mailing list password(s)
  • [Improvement] UI improvements (show attachment indicator in email archive, explain fwd errors/completed indicators)
  • [Improvement] Add list name in List-Subscribe / List-Unsubscribe headers (subject lines)
  • [Bug Fix] Fix issue when no iconv functionality is available for charset conversion
  • [Bug Fix] Fix PHP errors (PHP 8)
  • [Bug Fix] Saving WP user’s lists/groups will not cause incorrect error message
  • [Bug Fix] Do not show current date/time in send timestamp column when sending was not done
  • [Bug Fix] Fix some language typos


Release Date – October 20th, 2022

  • [Improvement] For address mode = TO (single recipient per email), pre-fill email address in unsubscribe links
  • [Improvement] Stop using $_SESSION to avoid problems with WP health check etc.
  • [Improvement] Introduce various filters for altering the subscribe/unsubscribe endpoints headers, text and buttons
  • [Improvement] Introduce filter wpmailster_email_processing_attachment_default_filename to override default attachment filename (mst_no_filename) if needed
  • [Bug Fix] Subscribe and unsubscribe dialogs can now be translated
  • [Bug Fix] Fixed unsubscribe problem: when for one email address, there is a both a WordPress and a WP Mailster user, both get unsubscribed
  • [Bug Fix] License key can be saved in WP Mailster settings if ad-hoc check/validation fails
  • [Bug Fix] Change license backend callbacks to be executed server side (to avoid issues with CSP / Content Security Policy blocking in browsers)
  • [Bug Fix] Remove several PHP notices


Release Date – August 23rd, 2022

  • [Improvement] Store log file now in wp-content/uploads/wp-mailster directory to avoid problems on plugin updates/upgrades/downgrades
  • [Bug Fix] mst_emails shortcode’s list ID (lid) filter works again
  • [Bug Fix] Goodbye/welcome messages were not sent in some situations where admin changed list memberships
  • [Bug Fix] Support special characters in passwords (slash, “/”, was missing)


Release Date – July 27th, 2022

  • [Improvement] Update minimal system requirements to WP 5.3 (from 4.3) and PHP 5.6 (from 5.5)
  • [Bug Fix] Storing of attachments with long MIME subtypes (e.g. MS Office formats like docx format with: VND.OPENXMLFORMATS-OFFICEDOCUMENT.WORDPROCESSINGML.DOCUMENT) is supported and will not crash mail retrieving
  • [Bug Fix] Fix issues managing users with apostrophe in their names (like O’Neil)
  • [Bug Fix] Fix issues recording send events for users with apostrophe in their names
  • [Bug Fix] Omit PHP warnings like “DOMDocument::loadHTML(): Tag o:p invalid in Entity”
  • [Bug Fix] Fix issue with timestamps not taking WP timezone settings into account
  • [Bug Fix] A “mail not forwarded” event not being sent out (due to random reasons) will not stop handling of mailing list mails (not cause email loop)
  • [Bug Fix] Failure to open the log file will not crash the process


Release Date – June 10th, 2022

  • [Feature] Introduce subscribe and unsubscribe shortcodes ([mst_subscribe] and [mst_unsubscribe])
  • [Improvement] UI optimization: full width for emails/lists/users/groups/servers/… table views
  • [Bug Fix] Fix for moderation mode: bounced/blocked/filtered emails will not produce a moderation request
  • [Bug Fix] Fix handling of certain binary attachments
  • [Bug Fix] Fix database issues (db maintenance) on WP multisite installations


Release Date – February 1st, 2022

  • [Improvement] CSV export also puts out the user description / notes
  • [Bug Fix] Increase plugin (lazy cronjob) stability to avoid edge cash crashes
  • [Bug Fix] Fix issue in CSV import
  • [Bug Fix] Show updated/created message when editing/saving/updating user
  • [Bug Fix] Show name of list being added in header