EverPress

Verifies your subscribers email addresses. Read more on the <a href="https://kb.mailster.co/reduce-false-signups-with-email-verification/?utm_campaign=wporg&utm_source=Email+Verify+for+Mailster&utm_medium=readme" rel="nofollow ugc">Mailster Knowledge base</a>
This plugin is no longer needed since Mailster 3.0!
<h3>Additional Info</h3>
<blockquote>
This Plugin requires <a href="https://mailster.co/?utm_campaign=wporg&utm_source=Email+Verify+for+Mailster&utm_medium=readme" rel="nofollow ugc">Mailster Newsletter Plugin for WordPress</a>
</blockquote>

Mailster Email Verify

The plugin will reject the email address if there is no such domain, but the SMTP ping to see whether the actual email address exists or not doesn't work.
Without this, it's not really useful.

MX checking works, SMTP doesn't

Verifies your subscribers email addresses. Read more on the Mailster Knowledge base

Formcrafts

This add-on allows you to add subscribers to your Mailster lists, with forms made with <a href="http://formcraft-wp.com/" rel="nofollow ugc">FormCraft</a>
Please note that this add-on works with <a href="http://formcraft-wp.com/" rel="nofollow ugc">FormCraft Premium</a>, and not <a href="https://wordpress.org/plugins/formcraft-form-builder/" rel="ugc">FormCraft Basic</a>

Mailster Add-On for FormCraft

Create gorgeous optin forms for your site  with FormCraft, and grow your Mailster list.

Mailster Email Verify vs Mailster Add-On for FormCraft