Mailster WordPress Newsletter Plugin

Plugin Banner

Mailster WordPress Newsletter Plugin

by EverPress

Download
Description

This free plugin is a Mailster compatibility tester

Mailster itself is a premium-only WordPress email newsletter and email marketing plugin. It is not distributed as a free download on WordPress.org.

This listing installs a free compatibility tester under the mailster plugin slug. Use it to verify that your WordPress site and hosting environment are ready for Mailster before you purchase a license.

After you activate the tester, open Mailster Tester in the WordPress admin and run the checks. The tester reviews:

  • PHP and WordPress version requirements
  • Required PHP capabilities (DOMDocument, fsockopen)
  • Memory limit recommendations
  • Whether wp_mail() can deliver a test message
  • Whether common SMTP-related TCP ports (25, 465, 587, 993, 2525) are reachable

When you are ready, get the full Mailster plugin from mailster.co.

Why choose Mailster for WordPress email newsletters?

Mailster is an easy-to-use email newsletter plugin for WordPress. Create, send, and track newsletter campaigns without a separate ESP account for your subscriber list—your data stays in your own WordPress database.

Capture subscribers and grow your list

Collect subscribers with signup forms on your website or blog. Import existing lists, manage unlimited subscribers, forms, and lists on a one-time license model (support and updates require an active license period).

Send posts, products, and custom content

Send your latest posts, WooCommerce products, events, or other custom post types as newsletters. The same content types can drive email automation.

Automate welcome series, drips, and follow-ups

Set up welcome emails, birthday campaigns, drip campaigns, follow-ups, auto-responders, and more. Mailster can run targeted journeys while you focus on your business.

Templates and campaign editor

Choose from more than 400 free and premium email templates. Build campaigns quickly with Mailster’s editor, or adapt designs with Mailster’s template markup language.

Deliverability and sending flexibility

Send with any email provider—professional SMTP/ESP services or your own server. Use RSS-to-email to turn new posts from a feed into automated campaigns. Time zone based sending helps reach subscribers when they are most likely to open.

Personalization, segmentation, and insights

Use merge tags for personalized content, segment audiences with Mailster’s metrics, and track opens, clicks, location, and other campaign activity in real time. Pre-check campaigns before you send so you can fix issues early.

Privacy and control

Mailster is designed for GDPR-conscious setups: subscriber data is stored in your WordPress database and is not handed to a third-party list host as the primary store. Capability management lets you control which team members can do what. Developers get hooks and filters to extend Mailster.

Integrations and add-ons

Mailster works alongside popular WordPress plugins and offers official add-ons. Browse templates, add-ons, and the knowledge base.

Mailster feature highlights

  • Subscriber capture forms and list management
  • Campaigns for posts, products, and custom post types
  • Welcome, birthday, drip, and follow-up automation
  • 400+ free and premium templates
  • RSS-to-email campaigns
  • Built-in email campaign pre-check
  • Send via any email provider / SMTP
  • Time zone based delivery
  • Merge tags and advanced segmentation
  • Campaign insights and reports
  • Public newsletter archive
  • GDPR-oriented self-hosted data
  • Capability management and developer hooks
  • Available in many languages

Important: Installing this WordPress.org plugin does not install the full premium Mailster product. Purchase and download Mailster from mailster.co after your environment passes the tester.

  1. Upload the entire mailster folder to the /wp-content/plugins/ directory, or install the zip via Plugins Add New Upload Plugin.
  2. Activate the plugin through the Plugins screen in WordPress.
  3. Open Mailster Tester in the admin menu and run the compatibility checks.
  4. Review any errors or warnings, fix hosting or WordPress issues as needed, then purchase the full Mailster plugin from mailster.co when you are ready.
Is this the full Mailster newsletter plugin?

No. This free WordPress.org plugin is a compatibility tester only. Mailster is premium-only and is sold at mailster.co.

What does the compatibility tester check?

It checks PHP and WordPress versions, DOMDocument and fsockopen support, memory limits, wp_mail() delivery, and reachability of common email-related TCP ports.

Do I need a Mailster license to run the tester?

No. The tester is free. You need a Mailster license only for the full email newsletter plugin.

Can I upgrade the tester plugin to the full Mailster plugin?

No. WordPress.org guidelines do not allow converting this free tester into the premium plugin via an in-place update. When you upload the full Mailster ZIP from your purchase, the installer replaces the tester files in place and deactivates this plugin so Mailster can take over.

Where do I get support for Mailster?

Use the Mailster knowledge base and Mailster support. WordPress.org support for this listing applies to the free tester plugin.

Is this plugin supported or developed

By ksaltik on January 15, 2026

Is this plugin supported or developed .

Awful performance and support

By ninjaneen on September 24, 2025

I don’t often take the time to write a review but the “support” for this plugin is absolutely abysmal. The last FOUR WEEKS of trying to switch from legacy Mailster to new forms has been excruciating. It’s been a complete waste of my time as a developer and a complete waste of my client’s budget, having me liase all this time only to have to give up because ‘support’ won’t help.

Firstly the ‘legacy’ forms were hacked and they were being used to send spam, so the hosting company took the website offline until the issue was sorted. I completely removed the legacy form, got the website back online, and then tried to switch to their new forms….. and then the fun really started!

Their documentation is awful. It’s not even basic. So I kept having to reach out to ask one excruciating question after the next, one question a day, one answer a day. The days and weeks dragged by and we still can’t create a ‘Mailster Homepage’ which is the new feature that replaced the ‘legacy’ feature.

This newsletter was used on a large health organisation website which is funded by the EU. Of course we’re not going to grant 3rd party access to a live website so that can start testing. ONE MONTH LATER and the issues are still not resolved, because ‘support’ have said that they won’t help. The reason? We don’t have a license for the staging/development site which they can use to troubleshoot the issue.

We have now moved to a popular 3rd party solution because this last issue was really just the last straw. When the plugin was still working it would take an entire TWO DAYS just to send ONE newsletter to a small list of 2400 subscribers, even after using their ‘intelligent email throttling” or whatever fancy name they give for a tool that makes no difference at all. We’re not on cheap hosting either. We have dedicated CPU and processors.

Don’t waste your time with this plugin.

Before you buy Mailster for WordPress

By Patryk (patryktarachon) on November 3, 2025

I’ve been using the plugin for 2 years, it works averagely. Since then they’ve only introduced up to 3 automations, which rarely work. It still doesn’t load blocks and constantly displays error messages. The worst-optimized newsletter plugin.

Considering autoresponders, I’ve tried many times to figure out why some work (despite the same settings) while others don’t send. I also don’t understand why some subscribers receive Auto-responder messages while others don’t, despite being added to the same lists. The time since they registered doesn’t differ from the time those who receive these messages.

The plugin requires a lot of patience from developers, not to mention non-technical users.

Total nightmare

By emma336 on June 28, 2023

What a nightmare of a plugin.

There are virtually no instructions on how to set it up, it’s unreliable and has lots of bugs. We had an issue with it trying to send hundreds of emails without knowing why it was doing it and there’s no way of knowing how to solve the issues.

Thank you

By Musabah-hati (musabah) on June 19, 2021

the plugin works very well. Thank you

Okay

By Tobias (tobiaseichner) on April 8, 2020

Plugin works as intended. Great.

update?

By StevenW123 on January 6, 2018

Hi, Are you planning to update this, please? Tested up to: 4.8.4 Also, is this the same plugin that features on Codecanyon? If so, it’s a nice plugin! What limitations are there on this version, please? Thanks, Steve

Great Newsletter Plugin!

By josemanuel8 on May 23, 2024

This is by far the most complete newsletter solution I came across. All built right into the WordPress dashboard without any subscriber limits for a one time fee. Love it!

2.0.3

  • fixed: plugin no longer fails to load when Composer vendor/ is missing after Freemius removal
  • changed: FAQ clarifies that installing the full Mailster ZIP replaces and deactivates the tester
  • changed: support links point to Mailster support instead of the retired account area

2.0.2

  • removed Freemius SDK

2.0.1

  • updated: readme

2.0.0

Completely rewritten from scratch

For further details please visit the changelog on the Mailster Homepage