by brandtoss 4.9 (32 reviews)

WP Mailster

Name: WP Mailster
Rating: 4.9 (32 reviews)
Author: brandtoss

WP Mailster allows your users to be part of a group and communicate by email without having to log into a website.

WP Mailster ranks #10,144 among WordPress.org plugins with 300+ active installations, is #511 of 3,634 in the Communication category, a 4.9/5 rating from 32 reviews, and was last updated Oct 18, 2026. Data from WordPress.org, refreshed twice daily — see methodology.

Compatible with WP 7.1

v1.9.2.0 Current Version v1.9.2.0

Updated 2 weeks ago Last Update on 18 Oct, 2026

Refreshed 2 days ago Last Refreshed on

#511 of 3,634 in Communication Top 25% by installs Downloads -71% this week Actively maintained

View on WordPress.org

Rank

#10,144

— No change

Active Installs

300+

-23.1%

KW Avg Position

— No change

Downloads

31K

+17 today

Support Resolved

— No change

Rating

98%

Review 4.9 out of 5

4.9 (32 reviews)

Next Milestone 400

Total Progress 78%

300+ 400+

323

Ranks to Climb

Growth Needed

8,000,000

Active Installs

Pro

Unlock Exact Install Count

See the precise estimated active installs for this plugin, calculated from real-time ranking data.

Exact install estimates within tiers
Track install growth over time
Milestone progress predictions

Upgrade to Pro

Need 22 more installs to reach 400+

Rank Changes

Current #10,144

Change

Best #

Upgrade to Pro

Unlock 30-day and 90-day rank history charts with a Pro subscription.

Upgrade Now

Active Installs Growth

Upgrade to Pro

Active Installs 0,000,000+

Growth +0.0%

Peak 0,000,000

Downloads Growth

Downloads

Growth

Peak

Upgrade to Pro

Unlock 30-day, 90-day, and yearly download history charts with a Pro subscription.

Upgrade Now

Reviews & Ratings

4.9

32 reviews

Overall 98%

31 (97%)

0 (0%)

1 (3%)

Security History

Source: WPVulnerability

15 known vulnerabilities on record · 12 in the last 24 months · checked 3 months ago

Jan 28, 2025

WP Mailster [wp-mailster] < 1.8.21.0

CVE-2025-24688 · Fixed in v1.8.21.0
Jan 6, 2025

WP Mailster [wp-mailster] < 1.8.18.0

CVE-2025-22303 · Fixed in v1.8.18.0
Dec 22, 2024

WP Mailster [wp-mailster] < 1.8.18.0

CVE-2025-24598 · Fixed in v1.8.18.0
Dec 11, 2024

WP Mailster [wp-mailster] < 1.8.18.0

CVE-2024-54355 · Fixed in v1.8.18.0
Dec 7, 2024

WP Mailster [wp-mailster] < 1.8.17.0

CVE-2025-24567 · Fixed in v1.8.17.0
Dec 2, 2024

WP Mailster [wp-mailster] < 1.8.17.0

CVE-2024-53804 · Fixed in v1.8.17.0
Dec 2, 2024

WP Mailster [wp-mailster] < 1.8.18.0

CVE-2024-11782 · Fixed in v1.8.18.0
Dec 2, 2024

WP Mailster [wp-mailster] < 1.8.17.0

CVE-2024-53807 · Fixed in v1.8.17.0
Dec 2, 2024

WP Mailster [wp-mailster] < 1.8.17.0

CVE-2024-53803 · Fixed in v1.8.17.0
Dec 2, 2024

WP Mailster [wp-mailster] < 1.8.17.0

CVE-2024-53805 · Fixed in v1.8.17.0

Showing the 10 most recent of 15 records.

Track This Plugin

Get detailed analytics, keyword tracking, and position alerts delivered to your inbox.

Start Tracking Free

Plugin Details

Version: 1.9.2.0
Last Updated: Oct 18, 2026
Requires WP: 5.3+
Tested Up To: 7.1
PHP Version: 7.4 or higher
Author: brandtoss

Support & Rating

Rating: ★ ★ ★ ★ ★ 4.9
Reviews: 32
Support Threads: 0
Resolved: 0%

Keywords

discussion list group email listserv mailing list mailman

Upgrade to Pro

Unlock keyword rankings, search positions, and detailed analytics with a Pro subscription.

Upgrade Now

Similar Plugins

Adminify – White Label, Admin Menu Editor, Login Customizer

6K+ installs

#2,757

Master Addons for Elementor – Elementor Addons, Widgets, Mega Menu Builder, Popup Builder, Widget Builder & Template Kits

WP Mail SMTP by WPForms – SMTP for Reliable Email Delivery with Gmail, Outlook, Amazon SES, Brevo, Other SMTP & More

4M+ installs

#12

MC4WP: Mailchimp for WordPress

1M+ installs

#35

Hostinger Reach – AI-Powered Email Marketing for WordPress

1M+ installs

#41

Popup Builder & Popup Maker for WordPress – OptinMonster Email Marketing and Lead Generation

FluentSMTP – WP Mail SMTP Plugin with Amazon SES, SendGrid, Mailgun, Postmark, Cloudflare, toSend, Gmail and Any SMTP

700K+ installs

#87

Joinchat – Enhanced “click to chat”

700K+ installs

#89

View all Communication plugins

TL;DR

AI summary of the plugin's readme

WP Mailster is for site owners who want to run an email discussion group without requiring members to log into the website. It solves two-way group communication by forwarding messages sent to a central address to all list members and relaying their replies back to the group.

Group communication through email
Works with any POP3/IMAP account
Manage recipients in WP admin
Subscribe/unsubscribe widgets
Organize users into groups
Forward replies to all recipients
Email archive for browsing mails
HTML emails and attachments support

Frequently Asked Questions

Common questions about WP Mailster

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.

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 sent/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.

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.

You might get an error message like this when checking the connection settings: “Certificate failure for [server] Server name does not match certificate” or “Certificate failure for [server] unable to get local issuer certificate”. This is often the case when you use your own mailing server (with a self-signed certificate). To get a connection established, you need to deactivate the automated certificate check. Do this by adding the following line in the special parameter box: /novalidate-cert

WP Mailster requires PHP 7.4 or newer for all mailbox backends. The legacy PHP IMAP backend needs the PHP IMAP extension for both IMAP and POP3. Ask your web host to enable it if you use this backend. The bundled Webklex backend can access IMAP mailboxes without the PHP IMAP extension. It requires PHP 7.4 or newer, the OpenSSL, mbstring, iconv and fileinfo extensions, and JSON support. WP Mailster 1.9.0 supports PHP 8.4 and 8.5 using this Webklex backend for IMAP mailboxes. The PHP IMAP extension was removed from the bundled PHP distribution in PHP 8.4 and moved to PECL; Webklex removes the need to install it for IMAP access. POP3 mailboxes still require the legacy backend and the PHP IMAP extension. Automatic backend selection prefers the legacy PHP IMAP backend when available. Google and Microsoft OAuth inboxes use Webklex.

Create or edit an inbox server in WP Mailster, select OAuth 2.0 and the provider, and enter your OAuth application's client ID and client secret. Register the exact OAuth Redirect URI shown in the server settings with your application provider. Select that server in the mailing list's mailbox settings, save the list, then use the provider's connect button to authorize the mailbox. Run the inbox connection check after authorization; successful authorization alone does not confirm that the mailbox permits IMAP access. Tokens are refreshed during regular mailbox retrieval. If access is revoked, reconnect the mailbox. OAuth support applies to incoming IMAP mail; configure outgoing SMTP separately.

In most situations this connection errors show up when your web hoster (where WordPress/WP Mailster is installed) is blocking outgoing connections such as connection attempts to 3rd party email servers. This is done to avoid spam sending. Please contact your web hoster, so they configure their firewall to allow you to send emails.

Your issue is very likely coming from a large email causing an PHP out of memory error. This is resulting from the fact that every PHP environment has a memory limit. This limit is hit when the email is tried to be retrieved from the mail server. Please remove this email from the mailing list in question. Either through a mail web-frontend or with the “Delete first email in inbox” tool the “Tools” section in the mailing list’s settings. In order to prevent have this happen in the future: Raise the PHP memory limit. Your web hoster can help you with that. Introduce a maximum email size for WP Mailster. You can find this setting in the “List behaviour” tab of the mailing lists settings. If larger emails are in the inbox, WP Mailster will not try to process them but simply delete it and tell the sender what happened.

A mailing list is a set of recipients that should all get the messages send to the mailing list’s email address. A group is a way of organizing users. Think of it like a bucket of users. It comes in handy if you want certain users be recipients of multiple mailing lists. Then you would not add the users directly to the recipients of a mailing list, but rather add a group. An example would be that you have three groups: Management, Project Coordinators and Developers. If you want to run a company-wide mailing list (e.g. all@example.com) and a project mailing list (e.g. project.import@example.com) then you would add all three groups (Management, Project Coordinators and Developers) as recipients of the company-wide mailing list only the Project Coordinators and Developers groups as recipients of the project mailing list

In case someone joins the project team you would only add the user to the Developers group. Then the user would be automatically be a recipient of both the project and the company-wide mailing list. The same thing applies if someone leaves: the user only needs to be removed form the groups and thus is automatically removed from the mailing lists that have this groups as the recipients. So to sum up: if you run many lists and have many users that are largely managed by the admin, then it might be handy to organize users in groups and add the groups as the recipients.