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.

Mailster WordPress Newsletter Plugin